js: fix core.Object, output order, static const fields

test/codegen/expect/dart/collection.js

Index: test/codegen/expect/dart/collection.js
diff --git a/test/codegen/expect/dart/collection.js b/test/codegen/expect/dart/collection.js
index 0c75709c32bd539de5896a81dafc566e32f9b0ad..465acee6792dc34eb971fd2720b3bf2894a4b199 100644
--- a/test/codegen/expect/dart/collection.js
+++ b/test/codegen/expect/dart/collection.js
@@ -1,2663 +1,2523 @@
 var collection;
 (function(exports) {
   'use strict';
-  let _length = Symbol('_length');
-  let _strings = Symbol('_strings');
-  let _nums = Symbol('_nums');
-  let _rest = Symbol('_rest');
-  let _keys = Symbol('_keys');
-  let _containsKey = Symbol('_containsKey');
-  let _getBucket = Symbol('_getBucket');
-  let _findBucketIndex = Symbol('_findBucketIndex');
-  let _computeKeys = Symbol('_computeKeys');
-  let _get = Symbol('_get');
-  let _addHashTableEntry = Symbol('_addHashTableEntry');
-  let _set = Symbol('_set');
-  let _computeHashCode = Symbol('_computeHashCode');
-  let _removeHashTableEntry = Symbol('_removeHashTableEntry');
-  let _remove = Symbol('_remove');
-  let _isStringKey = Symbol('_isStringKey');
-  let _isNumericKey = Symbol('_isNumericKey');
-  let _hasTableEntry = Symbol('_hasTableEntry');
-  let _getTableEntry = Symbol('_getTableEntry');
-  let _setTableEntry = Symbol('_setTableEntry');
-  let _deleteTableEntry = Symbol('_deleteTableEntry');
-  let _newHashTable = Symbol('_newHashTable');
-  let _HashMap$ = dart.generic(function(K, V) {
-    class _HashMap extends dart.Object {
-      _HashMap() {
-        this[_length] = 0;
-        this[_strings] = null;
-        this[_nums] = null;
-        this[_rest] = null;
-        this[_keys] = null;
+  let _source = Symbol('_source');
+  let UnmodifiableListView$ = dart.generic(function(E) {
+    class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
+      UnmodifiableListView(source) {
+        this[_source] = source;
+        super.UnmodifiableListBase();
       }
       get length() {
-        return this[_length];
-      }
-      get isEmpty() {
-        return this[_length] === 0;
-      }
-      get isNotEmpty() {
-        return !dart.notNull(this.isEmpty);
-      }
-      get keys() {
-        return new HashMapKeyIterable(this);
+        return this[_source].length;
       }
-      get values() {
-        return new _internal.MappedIterable(this.keys, ((each) => this.get(each)).bind(this));
+      get(index) {
+        return this[_source].elementAt(index);
       }
-      containsKey(key) {
-        if (_isStringKey(key)) {
-          let strings = this[_strings];
-          return strings === null ? false : _hasTableEntry(strings, key);
-        } else if (_isNumericKey(key)) {
-          let nums = this[_nums];
-          return nums === null ? false : _hasTableEntry(nums, key);
+    }
+    return UnmodifiableListView;
+  });
+  let UnmodifiableListView = UnmodifiableListView$(dart.dynamic);
+  // Function _defaultEquals: (dynamic, dynamic) → bool
+  function _defaultEquals(a, b) {
+    return dart.equals(a, b);
+  }
+  // Function _defaultHashCode: (dynamic) → int
+  function _defaultHashCode(a) {
+    return dart.as(dart.dload(a, 'hashCode'), core.int);
+  }
+  let HashMap$ = dart.generic(function(K, V) {
+    class HashMap extends core.Object {
+      HashMap(opt$) {
+        let equals = opt$.equals === void 0 ? null : opt$.equals;
+        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
+        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
+        if (isValidKey === null) {
+          if (hashCode === null) {
+            if (equals === null) {
+              return new _HashMap();
+            }
+            hashCode = _defaultHashCode;
+          } else {
+            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+              return new _IdentityHashMap();
+            }
+            if (equals === null) {
+              equals = _defaultEquals;
+            }
+          }
         } else {
-          return this[_containsKey](key);
+          if (hashCode === null) {
+            hashCode = _defaultHashCode;
+          }
+          if (equals === null) {
+            equals = _defaultEquals;
+          }
         }
+        return new _CustomHashMap(equals, hashCode, isValidKey);
       }
-      [_containsKey](key) {
-        let rest = this[_rest];
-        if (rest === null)
-          return false;
-        let bucket = this[_getBucket](rest, key);
-        return dart.notNull(this[_findBucketIndex](bucket, key)) >= 0;
-      }
-      containsValue(value) {
-        return this[_computeKeys]().any(((each) => dart.equals(this.get(each), value)).bind(this));
+      HashMap$identity() {
+        return new _IdentityHashMap();
       }
-      addAll(other) {
-        other.forEach(((key, value) => {
-          this.set(key, value);
-        }).bind(this));
+      HashMap$from(other) {
+        let result = new HashMap();
+        other.forEach((k, v) => {
+          result.set(k, dart.as(v, V));
+        });
+        return result;
       }
-      get(key) {
-        if (_isStringKey(key)) {
-          let strings = this[_strings];
-          return dart.as(strings === null ? null : _getTableEntry(strings, key), V);
-        } else if (_isNumericKey(key)) {
-          let nums = this[_nums];
-          return dart.as(nums === null ? null : _getTableEntry(nums, key), V);
-        } else {
-          return this[_get](key);
-        }
+      HashMap$fromIterable(iterable, opt$) {
+        let key = opt$.key === void 0 ? null : opt$.key;
+        let value = opt$.value === void 0 ? null : opt$.value;
+        let map = new HashMap();
+        Maps._fillMapWithMappedIterable(map, iterable, key, value);
+        return map;
       }
-      [_get](key) {
-        let rest = this[_rest];
-        if (rest === null)
-          return null;
-        let bucket = this[_getBucket](rest, key);
-        let index = this[_findBucketIndex](bucket, key);
-        return dart.as(dart.notNull(index) < 0 ? null : bucket[dart.notNull(index) + 1], V);
+      HashMap$fromIterables(keys, values) {
+        let map = new HashMap();
+        Maps._fillMapWithIterables(map, keys, values);
+        return map;
       }
-      set(key, value) {
-        if (_isStringKey(key)) {
-          let strings = this[_strings];
-          if (strings === null)
-            this[_strings] = strings = _newHashTable();
-          this[_addHashTableEntry](strings, key, value);
-        } else if (_isNumericKey(key)) {
-          let nums = this[_nums];
-          if (nums === null)
-            this[_nums] = nums = _newHashTable();
-          this[_addHashTableEntry](nums, key, value);
-        } else {
-          this[_set](key, value);
+    }
+    dart.defineNamedConstructor(HashMap, 'identity');
+    dart.defineNamedConstructor(HashMap, 'from');
+    dart.defineNamedConstructor(HashMap, 'fromIterable');
+    dart.defineNamedConstructor(HashMap, 'fromIterables');
+    return HashMap;
+  });
+  let HashMap = HashMap$(dart.dynamic, dart.dynamic);
+  let _newSet = Symbol('_newSet');
+  let _HashSetBase$ = dart.generic(function(E) {
+    class _HashSetBase extends SetBase$(E) {
+      difference(other) {
+        let result = this[_newSet]();
+        for (let element of this) {
+          if (!dart.notNull(other.contains(element)))
+            result.add(dart.as(element, E));
         }
+        return result;
       }
-      [_set](key, value) {
-        let rest = this[_rest];
-        if (rest === null)
-          this[_rest] = rest = _newHashTable();
-        let hash = this[_computeHashCode](key);
-        let bucket = rest[hash];
-        if (bucket === null) {
-          _setTableEntry(rest, hash, [key, value]);
-          this[_length] = dart.notNull(this[_length]) + 1;
-          this[_keys] = null;
-        } else {
-          let index = this[_findBucketIndex](bucket, key);
-          if (dart.notNull(index) >= 0) {
-            bucket[dart.notNull(index) + 1] = value;
-          } else {
-            bucket.push(key, value);
-            this[_length] = dart.notNull(this[_length]) + 1;
-            this[_keys] = null;
-          }
+      intersection(other) {
+        let result = this[_newSet]();
+        for (let element of this) {
+          if (other.contains(element))
+            result.add(dart.as(element, E));
         }
+        return result;
       }
-      putIfAbsent(key, ifAbsent) {
-        if (this.containsKey(key))
-          return this.get(key);
-        let value = ifAbsent();
-        this.set(key, value);
-        return value;
+      toSet() {
+        return ((_) => {
+          _.addAll(this);
+          return _;
+        }).bind(this)(this[_newSet]());
       }
-      remove(key) {
-        if (_isStringKey(key)) {
-          return this[_removeHashTableEntry](this[_strings], key);
-        } else if (_isNumericKey(key)) {
-          return this[_removeHashTableEntry](this[_nums], key);
+    }
+    return _HashSetBase;
+  });
+  let _HashSetBase = _HashSetBase$(dart.dynamic);
+  let HashSet$ = dart.generic(function(E) {
+    class HashSet extends core.Object {
+      HashSet(opt$) {
+        let equals = opt$.equals === void 0 ? null : opt$.equals;
+        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
+        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
+        if (isValidKey === null) {
+          if (hashCode === null) {
+            if (equals === null) {
+              return new _HashSet();
+            }
+            hashCode = _defaultHashCode;
+          } else {
+            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+              return new _IdentityHashSet();
+            }
+            if (equals === null) {
+              equals = _defaultEquals;
+            }
+          }
         } else {
-          return this[_remove](key);
+          if (hashCode === null) {
+            hashCode = _defaultHashCode;
+          }
+          if (equals === null) {
+            equals = _defaultEquals;
+          }
         }
+        return new _CustomHashSet(equals, hashCode, isValidKey);
       }
-      [_remove](key) {
-        let rest = this[_rest];
-        if (rest === null)
-          return null;
-        let bucket = this[_getBucket](rest, key);
-        let index = this[_findBucketIndex](bucket, key);
-        if (dart.notNull(index) < 0)
-          return null;
-        this[_length] = dart.notNull(this[_length]) - 1;
-        this[_keys] = null;
-        return dart.as(bucket.splice(index, 2)[1], V);
+      HashSet$identity() {
+        return new _IdentityHashSet();
       }
-      clear() {
-        if (dart.notNull(this[_length]) > 0) {
-          this[_strings] = this[_nums] = this[_rest] = this[_keys] = null;
-          this[_length] = 0;
-        }
+      HashSet$from(elements) {
+        let result = new HashSet();
+        for (let e of elements)
+          result.add(e);
+        return result;
       }
-      forEach(action) {
-        let keys = this[_computeKeys]();
-        for (let i = 0, length = keys.length; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let key = keys[i];
-          action(dart.as(key, K), this.get(key));
-          if (keys !== this[_keys]) {
-            throw new core.ConcurrentModificationError(this);
-          }
-        }
+    }
+    dart.defineNamedConstructor(HashSet, 'identity');
+    dart.defineNamedConstructor(HashSet, 'from');
+    return HashSet;
+  });
+  let HashSet = HashSet$(dart.dynamic);
+  let IterableMixin$ = dart.generic(function(E) {
+    class IterableMixin extends core.Object {
+      map(f) {
+        return new _internal.MappedIterable(this, f);
       }
-      [_computeKeys]() {
-        if (this[_keys] !== null)
-          return this[_keys];
-        let result = new core.List(this[_length]);
-        let index = 0;
-        let strings = this[_strings];
-        if (strings !== null) {
-          let names = Object.getOwnPropertyNames(strings);
-          let entries = names.length;
-          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
-            let key = names[i];
-            result[index] = key;
-            index = dart.notNull(index) + 1;
-          }
-        }
-        let nums = this[_nums];
-        if (nums !== null) {
-          let names = Object.getOwnPropertyNames(nums);
-          let entries = names.length;
-          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
-            let key = +names[i];
-            result[index] = key;
-            index = dart.notNull(index) + 1;
-          }
-        }
-        let rest = this[_rest];
-        if (rest !== null) {
-          let names = Object.getOwnPropertyNames(rest);
-          let entries = names.length;
-          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
-            let key = names[i];
-            let bucket = rest[key];
-            let length = bucket.length;
-            for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
-              let key = bucket[i];
-              result[index] = key;
-              index = dart.notNull(index) + 1;
-            }
-          }
-        }
-        dart.assert(index === this[_length]);
-        return this[_keys] = result;
+      where(f) {
+        return new _internal.WhereIterable(this, f);
       }
-      [_addHashTableEntry](table, key, value) {
-        if (!dart.notNull(_hasTableEntry(table, key))) {
-          this[_length] = dart.notNull(this[_length]) + 1;
-          this[_keys] = null;
-        }
-        _setTableEntry(table, key, value);
+      expand(f) {
+        return new _internal.ExpandIterable(this, f);
       }
-      [_removeHashTableEntry](table, key) {
-        if (dart.notNull(table !== null) && dart.notNull(_hasTableEntry(table, key))) {
-          let value = dart.as(_getTableEntry(table, key), V);
-          _deleteTableEntry(table, key);
-          this[_length] = dart.notNull(this[_length]) - 1;
-          this[_keys] = null;
-          return value;
-        } else {
-          return null;
+      contains(element) {
+        for (let e of this) {
+          if (dart.equals(e, element))
+            return true;
         }
+        return false;
       }
-      static [_isStringKey](key) {
-        return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
-      }
-      static [_isNumericKey](key) {
-        return dart.notNull(dart.is(key, core.num)) && (key & 0x3ffffff) === key;
+      forEach(f) {
+        for (let element of this)
+          f(element);
       }
-      [_computeHashCode](key) {
-        return dart.dload(key, 'hashCode') & 0x3ffffff;
+      reduce(combine) {
+        let iterator = this.iterator;
+        if (!dart.notNull(iterator.moveNext())) {
+          throw _internal.IterableElementError.noElement();
+        }
+        let value = iterator.current;
+        while (iterator.moveNext()) {
+          value = combine(value, iterator.current);
+        }
+        return value;
       }
-      static [_hasTableEntry](table, key) {
-        let entry = table[key];
-        return entry !== null;
+      fold(initialValue, combine) {
+        let value = initialValue;
+        for (let element of this)
+          value = combine(value, element);
+        return value;
       }
-      static [_getTableEntry](table, key) {
-        let entry = table[key];
-        return entry === table ? null : entry;
+      every(f) {
+        for (let element of this) {
+          if (!dart.notNull(f(element)))
+            return false;
+        }
+        return true;
       }
-      static [_setTableEntry](table, key, value) {
-        if (value === null) {
-          table[key] = table;
+      join(separator) {
+        if (separator === void 0)
+          separator = "";
+        let iterator = this.iterator;
+        if (!dart.notNull(iterator.moveNext()))
+          return "";
+        let buffer = new core.StringBuffer();
+        if (dart.notNull(separator === null) || dart.notNull(dart.equals(separator, ""))) {
+          do {
+            buffer.write(`${iterator.current}`);
+          } while (iterator.moveNext());
         } else {
-          table[key] = value;
+          buffer.write(`${iterator.current}`);
+          while (iterator.moveNext()) {
+            buffer.write(separator);
+            buffer.write(`${iterator.current}`);
+          }
         }
+        return buffer.toString();
       }
-      static [_deleteTableEntry](table, key) {
-        delete table[key];
-      }
-      [_getBucket](table, key) {
-        let hash = this[_computeHashCode](key);
-        return dart.as(table[hash], core.List);
-      }
-      [_findBucketIndex](bucket, key) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
-          if (dart.equals(bucket[i], key))
-            return i;
+      any(f) {
+        for (let element of this) {
+          if (f(element))
+            return true;
         }
-        return -1;
+        return false;
       }
-      static [_newHashTable]() {
-        let table = Object.create(null);
-        let temporaryKey = '<non-identifier-key>';
-        _setTableEntry(table, temporaryKey, table);
-        _deleteTableEntry(table, temporaryKey);
-        return table;
+      toList(opt$) {
+        let growable = opt$.growable === void 0 ? true : opt$.growable;
+        return new core.List.from(this, {growable: growable});
       }
-    }
-    return _HashMap;
-  });
-  let _HashMap = _HashMap$(dynamic, dynamic);
-  let _IdentityHashMap$ = dart.generic(function(K, V) {
-    class _IdentityHashMap extends _HashMap$(K, V) {
-      [_computeHashCode](key) {
-        return core.identityHashCode(key) & 0x3ffffff;
+      toSet() {
+        return new core.Set.from(this);
       }
-      [_findBucketIndex](bucket, key) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
-          if (core.identical(bucket[i], key))
-            return i;
+      get length() {
+        dart.assert(!dart.is(this, _internal.EfficientLength));
+        let count = 0;
+        let it = this.iterator;
+        while (it.moveNext()) {
+          count = dart.notNull(count) + 1;
         }
-        return -1;
+        return count;
       }
-    }
-    return _IdentityHashMap;
-  });
-  let _IdentityHashMap = _IdentityHashMap$(dynamic, dynamic);
-  let _equals = Symbol('_equals');
-  let _hashCode = Symbol('_hashCode');
-  let _validKey = Symbol('_validKey');
-  let _CustomHashMap$ = dart.generic(function(K, V) {
-    class _CustomHashMap extends _HashMap$(K, V) {
-      _CustomHashMap($_equals, $_hashCode, validKey) {
-        this[_equals] = $_equals;
-        this[_hashCode] = $_hashCode;
-        this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
-        super._HashMap();
+      get isEmpty() {
+        return !dart.notNull(this.iterator.moveNext());
       }
-      get(key) {
-        if (!dart.notNull(this[_validKey](key)))
-          return null;
-        return super._get(key);
+      get isNotEmpty() {
+        return !dart.notNull(this.isEmpty);
       }
-      set(key, value) {
-        super._set(key, value);
+      take(n) {
+        return new _internal.TakeIterable(this, n);
       }
-      containsKey(key) {
-        if (!dart.notNull(this[_validKey](key)))
-          return false;
-        return super._containsKey(key);
+      takeWhile(test) {
+        return new _internal.TakeWhileIterable(this, test);
       }
-      remove(key) {
-        if (!dart.notNull(this[_validKey](key)))
-          return null;
-        return super._remove(key);
+      skip(n) {
+        return new _internal.SkipIterable(this, n);
       }
-      [_computeHashCode](key) {
-        return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
+      skipWhile(test) {
+        return new _internal.SkipWhileIterable(this, test);
       }
-      [_findBucketIndex](bucket, key) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
-          if (this[_equals](dart.as(bucket[i], K), dart.as(key, K)))
-            return i;
+      get first() {
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext())) {
+          throw _internal.IterableElementError.noElement();
         }
-        return -1;
+        return dart.as(it.current, E);
+      }
+      get last() {
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext())) {
+          throw _internal.IterableElementError.noElement();
+        }
+        let result = null;
+        do {
+          result = dart.as(it.current, E);
+        } while (it.moveNext());
+        return result;
+      }
+      get single() {
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext()))
+          throw _internal.IterableElementError.noElement();
+        let result = dart.as(it.current, E);
+        if (it.moveNext())
+          throw _internal.IterableElementError.tooMany();
+        return result;
+      }
+      firstWhere(test, opt$) {
+        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
+        for (let element of this) {
+          if (test(element))
+            return element;
+        }
+        if (orElse !== null)
+          return orElse();
+        throw _internal.IterableElementError.noElement();
+      }
+      lastWhere(test, opt$) {
+        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
+        let result = null;
+        let foundMatching = false;
+        for (let element of this) {
+          if (test(element)) {
+            result = element;
+            foundMatching = true;
+          }
+        }
+        if (foundMatching)
+          return result;
+        if (orElse !== null)
+          return orElse();
+        throw _internal.IterableElementError.noElement();
+      }
+      singleWhere(test) {
+        let result = null;
+        let foundMatching = false;
+        for (let element of this) {
+          if (test(element)) {
+            if (foundMatching) {
+              throw _internal.IterableElementError.tooMany();
+            }
+            result = element;
+            foundMatching = true;
+          }
+        }
+        if (foundMatching)
+          return result;
+        throw _internal.IterableElementError.noElement();
+      }
+      elementAt(index) {
+        if (!(typeof index == number))
+          throw new core.ArgumentError.notNull("index");
+        core.RangeError.checkNotNegative(index, "index");
+        let elementIndex = 0;
+        for (let element of this) {
+          if (index === elementIndex)
+            return element;
+          elementIndex = dart.notNull(elementIndex) + 1;
+        }
+        throw new core.RangeError.index(index, this, "index", null, elementIndex);
       }
       toString() {
-        return Maps.mapToString(this);
+        return IterableBase.iterableToShortString(this, '(', ')');
       }
     }
-    return _CustomHashMap;
+    return IterableMixin;
   });
-  let _CustomHashMap = _CustomHashMap$(dynamic, dynamic);
-  let _map = Symbol('_map');
-  let HashMapKeyIterable$ = dart.generic(function(E) {
-    class HashMapKeyIterable extends IterableBase$(E) {
-      HashMapKeyIterable($_map) {
-        this[_map] = $_map;
-        super.IterableBase();
+  let IterableMixin = IterableMixin$(dart.dynamic);
+  let _isToStringVisiting = Symbol('_isToStringVisiting');
+  let _iterablePartsToStrings = Symbol('_iterablePartsToStrings');
+  let IterableBase$ = dart.generic(function(E) {
+    class IterableBase extends core.Object {
+      IterableBase() {
       }
-      get length() {
-        return dart.as(dart.dload(this[_map], '_length'), core.int);
+      map(f) {
+        return new _internal.MappedIterable(this, f);
       }
-      get isEmpty() {
-        return dart.equals(dart.dload(this[_map], '_length'), 0);
+      where(f) {
+        return new _internal.WhereIterable(this, f);
       }
-      get iterator() {
-        return new HashMapKeyIterator(this[_map], dart.as(dart.dinvoke(this[_map], '_computeKeys'), core.List));
+      expand(f) {
+        return new _internal.ExpandIterable(this, f);
       }
       contains(element) {
-        return dart.as(dart.dinvoke(this[_map], 'containsKey', element), core.bool);
+        for (let e of this) {
+          if (dart.equals(e, element))
+            return true;
+        }
+        return false;
       }
       forEach(f) {
-        let keys = dart.as(dart.dinvoke(this[_map], '_computeKeys'), core.List);
-        for (let i = 0, length = keys.length; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          f(dart.as(keys[i], E));
-          if (keys !== dart.dload(this[_map], '_keys')) {
-            throw new core.ConcurrentModificationError(this[_map]);
-          }
+        for (let element of this)
+          f(element);
+      }
+      reduce(combine) {
+        let iterator = this.iterator;
+        if (!dart.notNull(iterator.moveNext())) {
+          throw _internal.IterableElementError.noElement();
+        }
+        let value = iterator.current;
+        while (iterator.moveNext()) {
+          value = combine(value, iterator.current);
         }
+        return value;
       }
-    }
-    return HashMapKeyIterable;
-  });
-  let HashMapKeyIterable = HashMapKeyIterable$(dynamic);
-  let _offset = Symbol('_offset');
-  let _current = Symbol('_current');
-  let HashMapKeyIterator$ = dart.generic(function(E) {
-    class HashMapKeyIterator extends dart.Object {
-      HashMapKeyIterator($_map, $_keys) {
-        this[_map] = $_map;
-        this[_keys] = $_keys;
-        this[_offset] = 0;
-        this[_current] = null;
+      fold(initialValue, combine) {
+        let value = initialValue;
+        for (let element of this)
+          value = combine(value, element);
+        return value;
       }
-      get current() {
-        return this[_current];
+      every(f) {
+        for (let element of this) {
+          if (!dart.notNull(f(element)))
+            return false;
+        }
+        return true;
       }
-      moveNext() {
-        let keys = this[_keys];
-        let offset = this[_offset];
-        if (keys !== dart.dload(this[_map], '_keys')) {
-          throw new core.ConcurrentModificationError(this[_map]);
-        } else if (dart.notNull(offset) >= keys.length) {
-          this[_current] = null;
-          return false;
+      join(separator) {
+        if (separator === void 0)
+          separator = "";
+        let iterator = this.iterator;
+        if (!dart.notNull(iterator.moveNext()))
+          return "";
+        let buffer = new core.StringBuffer();
+        if (dart.notNull(separator === null) || dart.notNull(dart.equals(separator, ""))) {
+          do {
+            buffer.write(`${iterator.current}`);
+          } while (iterator.moveNext());
         } else {
-          this[_current] = dart.as(keys[offset], E);
-          this[_offset] = dart.notNull(offset) + 1;
-          return true;
+          buffer.write(`${iterator.current}`);
+          while (iterator.moveNext()) {
+            buffer.write(separator);
+            buffer.write(`${iterator.current}`);
+          }
         }
+        return buffer.toString();
       }
-    }
-    return HashMapKeyIterator;
-  });
-  let HashMapKeyIterator = HashMapKeyIterator$(dynamic);
-  let _first = Symbol('_first');
-  let _last = Symbol('_last');
-  let _modifications = Symbol('_modifications');
-  let _value = Symbol('_value');
-  let _newLinkedCell = Symbol('_newLinkedCell');
-  let _unlinkCell = Symbol('_unlinkCell');
-  let _modified = Symbol('_modified');
-  let _key = Symbol('_key');
-  let _next = Symbol('_next');
-  let _previous = Symbol('_previous');
-  let _LinkedHashMap$ = dart.generic(function(K, V) {
-    class _LinkedHashMap extends dart.Object {
-      _LinkedHashMap() {
-        this[_length] = 0;
-        this[_strings] = null;
-        this[_nums] = null;
-        this[_rest] = null;
-        this[_first] = null;
-        this[_last] = null;
-        this[_modifications] = 0;
+      any(f) {
+        for (let element of this) {
+          if (f(element))
+            return true;
+        }
+        return false;
+      }
+      toList(opt$) {
+        let growable = opt$.growable === void 0 ? true : opt$.growable;
+        return new core.List.from(this, {growable: growable});
+      }
+      toSet() {
+        return new core.Set.from(this);
       }
       get length() {
-        return this[_length];
+        dart.assert(!dart.is(this, _internal.EfficientLength));
+        let count = 0;
+        let it = this.iterator;
+        while (it.moveNext()) {
+          count = dart.notNull(count) + 1;
+        }
+        return count;
       }
       get isEmpty() {
-        return this[_length] === 0;
+        return !dart.notNull(this.iterator.moveNext());
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
-      get keys() {
-        return new LinkedHashMapKeyIterable(this);
-      }
-      get values() {
-        return new _internal.MappedIterable(this.keys, ((each) => this.get(each)).bind(this));
+      take(n) {
+        return new _internal.TakeIterable(this, n);
       }
-      containsKey(key) {
-        if (_isStringKey(key)) {
-          let strings = this[_strings];
-          if (strings === null)
-            return false;
-          let cell = dart.as(_getTableEntry(strings, key), LinkedHashMapCell);
-          return cell !== null;
-        } else if (_isNumericKey(key)) {
-          let nums = this[_nums];
-          if (nums === null)
-            return false;
-          let cell = dart.as(_getTableEntry(nums, key), LinkedHashMapCell);
-          return cell !== null;
-        } else {
-          return this[_containsKey](key);
-        }
+      takeWhile(test) {
+        return new _internal.TakeWhileIterable(this, test);
       }
-      [_containsKey](key) {
-        let rest = this[_rest];
-        if (rest === null)
-          return false;
-        let bucket = this[_getBucket](rest, key);
-        return dart.notNull(this[_findBucketIndex](bucket, key)) >= 0;
+      skip(n) {
+        return new _internal.SkipIterable(this, n);
       }
-      containsValue(value) {
-        return this.keys.any(((each) => dart.equals(this.get(each), value)).bind(this));
+      skipWhile(test) {
+        return new _internal.SkipWhileIterable(this, test);
       }
-      addAll(other) {
-        other.forEach(((key, value) => {
-          this.set(key, value);
-        }).bind(this));
+      get first() {
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext())) {
+          throw _internal.IterableElementError.noElement();
+        }
+        return dart.as(it.current, E);
       }
-      get(key) {
-        if (_isStringKey(key)) {
-          let strings = this[_strings];
-          if (strings === null)
-            return null;
-          let cell = dart.as(_getTableEntry(strings, key), LinkedHashMapCell);
-          return dart.as(cell === null ? null : cell[_value], V);
-        } else if (_isNumericKey(key)) {
-          let nums = this[_nums];
-          if (nums === null)
-            return null;
-          let cell = dart.as(_getTableEntry(nums, key), LinkedHashMapCell);
-          return dart.as(cell === null ? null : cell[_value], V);
-        } else {
-          return this[_get](key);
+      get last() {
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext())) {
+          throw _internal.IterableElementError.noElement();
         }
+        let result = null;
+        do {
+          result = dart.as(it.current, E);
+        } while (it.moveNext());
+        return result;
       }
-      [_get](key) {
-        let rest = this[_rest];
-        if (rest === null)
-          return null;
-        let bucket = this[_getBucket](rest, key);
-        let index = this[_findBucketIndex](bucket, key);
-        if (dart.notNull(index) < 0)
-          return null;
-        let cell = dart.as(bucket[index], LinkedHashMapCell);
-        return dart.as(cell[_value], V);
+      get single() {
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext()))
+          throw _internal.IterableElementError.noElement();
+        let result = dart.as(it.current, E);
+        if (it.moveNext())
+          throw _internal.IterableElementError.tooMany();
+        return result;
       }
-      set(key, value) {
-        if (_isStringKey(key)) {
-          let strings = this[_strings];
-          if (strings === null)
-            this[_strings] = strings = _newHashTable();
-          this[_addHashTableEntry](strings, key, value);
-        } else if (_isNumericKey(key)) {
-          let nums = this[_nums];
-          if (nums === null)
-            this[_nums] = nums = _newHashTable();
-          this[_addHashTableEntry](nums, key, value);
-        } else {
-          this[_set](key, value);
+      firstWhere(test, opt$) {
+        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
+        for (let element of this) {
+          if (test(element))
+            return element;
         }
+        if (orElse !== null)
+          return orElse();
+        throw _internal.IterableElementError.noElement();
       }
-      [_set](key, value) {
-        let rest = this[_rest];
-        if (rest === null)
-          this[_rest] = rest = _newHashTable();
-        let hash = this[_computeHashCode](key);
-        let bucket = rest[hash];
-        if (bucket === null) {
-          let cell = this[_newLinkedCell](key, value);
-          _setTableEntry(rest, hash, [cell]);
-        } else {
-          let index = this[_findBucketIndex](bucket, key);
-          if (dart.notNull(index) >= 0) {
-            let cell = dart.as(bucket[index], LinkedHashMapCell);
-            cell[_value] = value;
-          } else {
-            let cell = this[_newLinkedCell](key, value);
-            bucket.push(cell);
+      lastWhere(test, opt$) {
+        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
+        let result = null;
+        let foundMatching = false;
+        for (let element of this) {
+          if (test(element)) {
+            result = element;
+            foundMatching = true;
           }
         }
+        if (foundMatching)
+          return result;
+        if (orElse !== null)
+          return orElse();
+        throw _internal.IterableElementError.noElement();
       }
-      putIfAbsent(key, ifAbsent) {
-        if (this.containsKey(key))
-          return this.get(key);
-        let value = ifAbsent();
-        this.set(key, value);
-        return value;
-      }
-      remove(key) {
-        if (_isStringKey(key)) {
-          return this[_removeHashTableEntry](this[_strings], key);
-        } else if (_isNumericKey(key)) {
-          return this[_removeHashTableEntry](this[_nums], key);
-        } else {
-          return this[_remove](key);
+      singleWhere(test) {
+        let result = null;
+        let foundMatching = false;
+        for (let element of this) {
+          if (test(element)) {
+            if (foundMatching) {
+              throw _internal.IterableElementError.tooMany();
+            }
+            result = element;
+            foundMatching = true;
+          }
         }
+        if (foundMatching)
+          return result;
+        throw _internal.IterableElementError.noElement();
       }
-      [_remove](key) {
-        let rest = this[_rest];
-        if (rest === null)
-          return null;
-        let bucket = this[_getBucket](rest, key);
-        let index = this[_findBucketIndex](bucket, key);
-        if (dart.notNull(index) < 0)
-          return null;
-        let cell = dart.as(bucket.splice(index, 1)[0], LinkedHashMapCell);
-        this[_unlinkCell](cell);
-        return dart.as(cell[_value], V);
-      }
-      clear() {
-        if (dart.notNull(this[_length]) > 0) {
-          this[_strings] = this[_nums] = this[_rest] = this[_first] = this[_last] = null;
-          this[_length] = 0;
-          this[_modified]();
+      elementAt(index) {
+        if (!(typeof index == number))
+          throw new core.ArgumentError.notNull("index");
+        core.RangeError.checkNotNegative(index, "index");
+        let elementIndex = 0;
+        for (let element of this) {
+          if (index === elementIndex)
+            return element;
+          elementIndex = dart.notNull(elementIndex) + 1;
         }
+        throw new core.RangeError.index(index, this, "index", null, elementIndex);
       }
-      forEach(action) {
-        let cell = this[_first];
-        let modifications = this[_modifications];
-        while (cell !== null) {
-          action(dart.as(cell[_key], K), dart.as(cell[_value], V));
-          if (modifications !== this[_modifications]) {
-            throw new core.ConcurrentModificationError(this);
+      toString() {
+        return iterableToShortString(this, '(', ')');
+      }
+      static iterableToShortString(iterable, leftDelimiter, rightDelimiter) {
+        if (leftDelimiter === void 0)
+          leftDelimiter = '(';
+        if (rightDelimiter === void 0)
+          rightDelimiter = ')';
+        if (_isToStringVisiting(iterable)) {
+          if (dart.notNull(dart.equals(leftDelimiter, "(")) && dart.notNull(dart.equals(rightDelimiter, ")"))) {
+            return "(...)";
           }
-          cell = cell[_next];
+          return `${leftDelimiter}...${rightDelimiter}`;
         }
-      }
-      [_addHashTableEntry](table, key, value) {
-        let cell = dart.as(_getTableEntry(table, key), LinkedHashMapCell);
-        if (cell === null) {
-          _setTableEntry(table, key, this[_newLinkedCell](key, value));
-        } else {
-          cell[_value] = value;
+        let parts = new List.from([]);
+        _toStringVisiting.add(iterable);
+        try {
+          _iterablePartsToStrings(iterable, parts);
+        } finally {
+          dart.assert(core.identical(_toStringVisiting.last, iterable));
+          _toStringVisiting.removeLast();
         }
+        return ((_) => {
+          _.writeAll(parts, ", ");
+          _.write(rightDelimiter);
+          return _;
+        }).bind(this)(new core.StringBuffer(leftDelimiter)).toString();
       }
-      [_removeHashTableEntry](table, key) {
-        if (table === null)
-          return null;
-        let cell = dart.as(_getTableEntry(table, key), LinkedHashMapCell);
-        if (cell === null)
-          return null;
-        this[_unlinkCell](cell);
-        _deleteTableEntry(table, key);
-        return dart.as(cell[_value], V);
-      }
-      [_modified]() {
-        this[_modifications] = dart.notNull(this[_modifications]) + 1 & 67108863;
-      }
-      [_newLinkedCell](key, value) {
-        let cell = new LinkedHashMapCell(key, value);
-        if (this[_first] === null) {
-          this[_first] = this[_last] = cell;
-        } else {
-          let last = this[_last];
-          cell[_previous] = last;
-          this[_last] = last[_next] = cell;
+      static iterableToFullString(iterable, leftDelimiter, rightDelimiter) {
+        if (leftDelimiter === void 0)
+          leftDelimiter = '(';
+        if (rightDelimiter === void 0)
+          rightDelimiter = ')';
+        if (_isToStringVisiting(iterable)) {
+          return `${leftDelimiter}...${rightDelimiter}`;
         }
-        this[_length] = dart.notNull(this[_length]) + 1;
-        this[_modified]();
-        return cell;
+        let buffer = new core.StringBuffer(leftDelimiter);
+        _toStringVisiting.add(iterable);
+        try {
+          buffer.writeAll(iterable, ", ");
+        } finally {
+          dart.assert(core.identical(_toStringVisiting.last, iterable));
+          _toStringVisiting.removeLast();
+        }
+        buffer.write(rightDelimiter);
+        return buffer.toString();
       }
-      [_unlinkCell](cell) {
-        let previous = cell[_previous];
-        let next = cell[_next];
-        if (previous === null) {
-          dart.assert(dart.equals(cell, this[_first]));
-          this[_first] = next;
-        } else {
-          previous[_next] = next;
+      static [_isToStringVisiting](o) {
+        for (let i = 0; dart.notNull(i) < dart.notNull(_toStringVisiting.length); i = dart.notNull(i) + 1) {
+          if (core.identical(o, _toStringVisiting.get(i)))
+            return true;
         }
-        if (next === null) {
-          dart.assert(dart.equals(cell, this[_last]));
-          this[_last] = previous;
+        return false;
+      }
+      static [_iterablePartsToStrings](iterable, parts) {
+        let LENGTH_LIMIT = 80;
+        let HEAD_COUNT = 3;
+        let TAIL_COUNT = 2;
+        let MAX_COUNT = 100;
+        let OVERHEAD = 2;
+        let ELLIPSIS_SIZE = 3;
+        let length = 0;
+        let count = 0;
+        let it = iterable.iterator;
+        while (dart.notNull(length) < dart.notNull(LENGTH_LIMIT) || dart.notNull(count) < dart.notNull(HEAD_COUNT)) {
+          if (!dart.notNull(it.moveNext()))
+            return;
+          let next = `${it.current}`;
+          parts.add(next);
+          length = dart.notNull(next.length) + dart.notNull(OVERHEAD);
+          count = dart.notNull(count) + 1;
+        }
+        let penultimateString = null;
+        let ultimateString = null;
+        let penultimate = null;
+        let ultimate = null;
+        if (!dart.notNull(it.moveNext())) {
+          if (dart.notNull(count) <= dart.notNull(HEAD_COUNT) + dart.notNull(TAIL_COUNT))
+            return;
+          ultimateString = dart.as(parts.removeLast(), core.String);
+          penultimateString = dart.as(parts.removeLast(), core.String);
         } else {
-          next[_previous] = previous;
+          penultimate = it.current;
+          count = dart.notNull(count) + 1;
+          if (!dart.notNull(it.moveNext())) {
+            if (dart.notNull(count) <= dart.notNull(HEAD_COUNT) + 1) {
+              parts.add(`${penultimate}`);
+              return;
+            }
+            ultimateString = `${penultimate}`;
+            penultimateString = dart.as(parts.removeLast(), core.String);
+            length = dart.notNull(ultimateString.length) + dart.notNull(OVERHEAD);
+          } else {
+            ultimate = it.current;
+            count = dart.notNull(count) + 1;
+            dart.assert(dart.notNull(count) < dart.notNull(MAX_COUNT));
+            while (it.moveNext()) {
+              penultimate = ultimate;
+              ultimate = it.current;
+              count = dart.notNull(count) + 1;
+              if (dart.notNull(count) > dart.notNull(MAX_COUNT)) {
+                while (dart.notNull(length) > dart.notNull(LENGTH_LIMIT) - dart.notNull(ELLIPSIS_SIZE) - dart.notNull(OVERHEAD) && dart.notNull(count) > dart.notNull(HEAD_COUNT)) {
+                  length = dart.as(dart.dbinary(dart.dload(parts.removeLast(), 'length'), '+', OVERHEAD), core.int);
+                  count = dart.notNull(count) - 1;
+                }
+                parts.add("...");
+                return;
+              }
+            }
+            penultimateString = `${penultimate}`;
+            ultimateString = `${ultimate}`;
+            length = dart.notNull(ultimateString.length) + dart.notNull(penultimateString.length) + 2 * dart.notNull(OVERHEAD);
+          }
         }
-        this[_length] = dart.notNull(this[_length]) - 1;
-        this[_modified]();
-      }
-      static [_isStringKey](key) {
-        return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
-      }
-      static [_isNumericKey](key) {
-        return dart.notNull(dart.is(key, core.num)) && (key & 0x3ffffff) === key;
-      }
-      [_computeHashCode](key) {
-        return dart.dload(key, 'hashCode') & 0x3ffffff;
+        let elision = null;
+        if (dart.notNull(count) > dart.notNull(parts.length) + dart.notNull(TAIL_COUNT)) {
+          elision = "...";
+          length = dart.notNull(ELLIPSIS_SIZE) + dart.notNull(OVERHEAD);
+        }
+        while (dart.notNull(length) > dart.notNull(LENGTH_LIMIT) && dart.notNull(parts.length) > dart.notNull(HEAD_COUNT)) {
+          length = dart.as(dart.dbinary(dart.dload(parts.removeLast(), 'length'), '+', OVERHEAD), core.int);
+          if (elision === null) {
+            elision = "...";
+            length = dart.notNull(ELLIPSIS_SIZE) + dart.notNull(OVERHEAD);
+          }
+        }
+        if (elision !== null) {
+          parts.add(elision);
+        }
+        parts.add(penultimateString);
+        parts.add(ultimateString);
       }
-      static [_getTableEntry](table, key) {
-        return table[key];
+    }
+    dart.defineLazyProperties(IterableBase, {
+      get _toStringVisiting() {
+        return new List.from([]);
       }
-      static [_setTableEntry](table, key, value) {
-        dart.assert(value !== null);
-        table[key] = value;
+    });
+    return IterableBase;
+  });
+  let IterableBase = IterableBase$(dart.dynamic);
+  let _iterator = Symbol('_iterator');
+  let _state = Symbol('_state');
+  let _move = Symbol('_move');
+  let HasNextIterator$ = dart.generic(function(E) {
+    class HasNextIterator extends core.Object {
+      HasNextIterator($_iterator) {
+        this[_iterator] = $_iterator;
+        this[_state] = HasNextIterator._NOT_MOVED_YET;
       }
-      static [_deleteTableEntry](table, key) {
-        delete table[key];
+      get hasNext() {
+        if (this[_state] === HasNextIterator._NOT_MOVED_YET)
+          this[_move]();
+        return this[_state] === HasNextIterator._HAS_NEXT_AND_NEXT_IN_CURRENT;
       }
-      [_getBucket](table, key) {
-        let hash = this[_computeHashCode](key);
-        return dart.as(table[hash], core.List);
+      next() {
+        if (!dart.notNull(this.hasNext))
+          throw new core.StateError("No more elements");
+        dart.assert(this[_state] === HasNextIterator._HAS_NEXT_AND_NEXT_IN_CURRENT);
+        let result = dart.as(this[_iterator].current, E);
+        this[_move]();
+        return result;
       }
-      [_findBucketIndex](bucket, key) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (dart.equals(cell[_key], key))
-            return i;
+      [_move]() {
+        if (this[_iterator].moveNext()) {
+          this[_state] = HasNextIterator._HAS_NEXT_AND_NEXT_IN_CURRENT;
+        } else {
+          this[_state] = HasNextIterator._NO_NEXT;
         }
-        return -1;
-      }
-      static [_newHashTable]() {
-        let table = Object.create(null);
-        let temporaryKey = '<non-identifier-key>';
-        _setTableEntry(table, temporaryKey, table);
-        _deleteTableEntry(table, temporaryKey);
-        return table;
-      }
-      toString() {
-        return Maps.mapToString(this);
       }
     }
-    return _LinkedHashMap;
+    HasNextIterator._HAS_NEXT_AND_NEXT_IN_CURRENT = 0;
+    HasNextIterator._NO_NEXT = 1;
+    HasNextIterator._NOT_MOVED_YET = 2;
+    return HasNextIterator;
   });
-  let _LinkedHashMap = _LinkedHashMap$(dynamic, dynamic);
-  let _LinkedIdentityHashMap$ = dart.generic(function(K, V) {
-    class _LinkedIdentityHashMap extends _LinkedHashMap$(K, V) {
-      [_computeHashCode](key) {
-        return core.identityHashCode(key) & 0x3ffffff;
-      }
-      [_findBucketIndex](bucket, key) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (core.identical(cell[_key], key))
-            return i;
+  let HasNextIterator = HasNextIterator$(dart.dynamic);
+  let LinkedHashMap$ = dart.generic(function(K, V) {
+    class LinkedHashMap extends core.Object {
+      LinkedHashMap(opt$) {
+        let equals = opt$.equals === void 0 ? null : opt$.equals;
+        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
+        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
+        if (isValidKey === null) {
+          if (hashCode === null) {
+            if (equals === null) {
+              return new _LinkedHashMap();
+            }
+            hashCode = _defaultHashCode;
+          } else {
+            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+              return new _LinkedIdentityHashMap();
+            }
+            if (equals === null) {
+              equals = _defaultEquals;
+            }
+          }
+        } else {
+          if (hashCode === null) {
+            hashCode = _defaultHashCode;
+          }
+          if (equals === null) {
+            equals = _defaultEquals;
+          }
         }
-        return -1;
-      }
-    }
-    return _LinkedIdentityHashMap;
-  });
-  let _LinkedIdentityHashMap = _LinkedIdentityHashMap$(dynamic, dynamic);
-  let _LinkedCustomHashMap$ = dart.generic(function(K, V) {
-    class _LinkedCustomHashMap extends _LinkedHashMap$(K, V) {
-      _LinkedCustomHashMap($_equals, $_hashCode, validKey) {
-        this[_equals] = $_equals;
-        this[_hashCode] = $_hashCode;
-        this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
-        super._LinkedHashMap();
+        return new _LinkedCustomHashMap(equals, hashCode, isValidKey);
       }
-      get(key) {
-        if (!dart.notNull(this[_validKey](key)))
-          return null;
-        return super._get(key);
+      LinkedHashMap$identity() {
+        return new _LinkedIdentityHashMap();
       }
-      set(key, value) {
-        super._set(key, value);
+      LinkedHashMap$from(other) {
+        let result = new LinkedHashMap();
+        other.forEach((k, v) => {
+          result.set(k, dart.as(v, V));
+        });
+        return result;
       }
-      containsKey(key) {
-        if (!dart.notNull(this[_validKey](key)))
-          return false;
-        return super._containsKey(key);
+      LinkedHashMap$fromIterable(iterable, opt$) {
+        let key = opt$.key === void 0 ? null : opt$.key;
+        let value = opt$.value === void 0 ? null : opt$.value;
+        let map = new LinkedHashMap();
+        Maps._fillMapWithMappedIterable(map, iterable, key, value);
+        return map;
       }
-      remove(key) {
-        if (!dart.notNull(this[_validKey](key)))
-          return null;
-        return super._remove(key);
+      LinkedHashMap$fromIterables(keys, values) {
+        let map = new LinkedHashMap();
+        Maps._fillMapWithIterables(map, keys, values);
+        return map;
       }
-      [_computeHashCode](key) {
-        return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
+      LinkedHashMap$_literal(keyValuePairs) {
+        return dart.as(_js_helper.fillLiteralMap(keyValuePairs, new _LinkedHashMap()), LinkedHashMap$(K, V));
       }
-      [_findBucketIndex](bucket, key) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (this[_equals](dart.as(cell[_key], K), dart.as(key, K)))
-            return i;
-        }
-        return -1;
+      LinkedHashMap$_empty() {
+        return new _LinkedHashMap();
       }
     }
-    return _LinkedCustomHashMap;
+    dart.defineNamedConstructor(LinkedHashMap, 'identity');
+    dart.defineNamedConstructor(LinkedHashMap, 'from');
+    dart.defineNamedConstructor(LinkedHashMap, 'fromIterable');
+    dart.defineNamedConstructor(LinkedHashMap, 'fromIterables');
+    dart.defineNamedConstructor(LinkedHashMap, '_literal');
+    dart.defineNamedConstructor(LinkedHashMap, '_empty');
+    return LinkedHashMap;
   });
-  let _LinkedCustomHashMap = _LinkedCustomHashMap$(dynamic, dynamic);
-  class LinkedHashMapCell extends dart.Object {
-    LinkedHashMapCell($_key, $_value) {
-      this[_key] = $_key;
-      this[_value] = $_value;
-      this[_next] = null;
-      this[_previous] = null;
+  let LinkedHashMap = LinkedHashMap$(dart.dynamic, dart.dynamic);
+  let LinkedHashSet$ = dart.generic(function(E) {
+    class LinkedHashSet extends core.Object {
+      LinkedHashSet(opt$) {
+        let equals = opt$.equals === void 0 ? null : opt$.equals;
+        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
+        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
+        if (isValidKey === null) {
+          if (hashCode === null) {
+            if (equals === null) {
+              return new _LinkedHashSet();
+            }
+            hashCode = _defaultHashCode;
+          } else {
+            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+              return new _LinkedIdentityHashSet();
+            }
+            if (equals === null) {
+              equals = _defaultEquals;
+            }
+          }
+        } else {
+          if (hashCode === null) {
+            hashCode = _defaultHashCode;
+          }
+          if (equals === null) {
+            equals = _defaultEquals;
+          }
+        }
+        return new _LinkedCustomHashSet(equals, hashCode, isValidKey);
+      }
+      LinkedHashSet$identity() {
+        return new _LinkedIdentityHashSet();
+      }
+      LinkedHashSet$from(elements) {
+        let result = new LinkedHashSet();
+        for (let element of elements) {
+          result.add(element);
+        }
+        return result;
+      }
     }
-  }
-  let LinkedHashMapKeyIterable$ = dart.generic(function(E) {
-    class LinkedHashMapKeyIterable extends IterableBase$(E) {
-      LinkedHashMapKeyIterable($_map) {
-        this[_map] = $_map;
+    dart.defineNamedConstructor(LinkedHashSet, 'identity');
+    dart.defineNamedConstructor(LinkedHashSet, 'from');
+    return LinkedHashSet;
+  });
+  let LinkedHashSet = LinkedHashSet$(dart.dynamic);
+  let _modificationCount = Symbol('_modificationCount');
+  let _length = Symbol('_length');
+  let _next = Symbol('_next');
+  let _previous = Symbol('_previous');
+  let _insertAfter = Symbol('_insertAfter');
+  let _list = Symbol('_list');
+  let _unlink = Symbol('_unlink');
+  let LinkedList$ = dart.generic(function(E) {
+    class LinkedList extends IterableBase$(E) {
+      LinkedList() {
+        this[_modificationCount] = 0;
+        this[_length] = 0;
+        this[_next] = null;
+        this[_previous] = null;
         super.IterableBase();
+        this[_next] = this[_previous] = this;
       }
-      get length() {
-        return dart.as(dart.dload(this[_map], '_length'), core.int);
+      addFirst(entry) {
+        this[_insertAfter](this, entry);
       }
-      get isEmpty() {
-        return dart.equals(dart.dload(this[_map], '_length'), 0);
+      add(entry) {
+        this[_insertAfter](this[_previous], entry);
+      }
+      addAll(entries) {
+        entries.forEach(((entry) => this[_insertAfter](this[_previous], dart.as(entry, E))).bind(this));
+      }
+      remove(entry) {
+        if (!dart.equals(entry[_list], this))
+          return false;
+        this[_unlink](entry);
+        return true;
       }
       get iterator() {
-        return new LinkedHashMapKeyIterator(this[_map], dart.as(dart.dload(this[_map], '_modifications'), core.int));
+        return new _LinkedListIterator(this);
       }
-      contains(element) {
-        return dart.as(dart.dinvoke(this[_map], 'containsKey', element), core.bool);
+      get length() {
+        return this[_length];
       }
-      forEach(f) {
-        let cell = dart.as(dart.dload(this[_map], '_first'), LinkedHashMapCell);
-        let modifications = dart.as(dart.dload(this[_map], '_modifications'), core.int);
-        while (cell !== null) {
-          f(dart.as(cell[_key], E));
-          if (modifications !== dart.dload(this[_map], '_modifications')) {
-            throw new core.ConcurrentModificationError(this[_map]);
+      clear() {
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        let next = this[_next];
+        while (!dart.notNull(core.identical(next, this))) {
+          let entry = dart.as(next, E);
+          next = entry[_next];
+          entry[_next] = entry[_previous] = entry[_list] = null;
+        }
+        this[_next] = this[_previous] = this;
+        this[_length] = 0;
+      }
+      get first() {
+        if (core.identical(this[_next], this)) {
+          throw new core.StateError('No such element');
+        }
+        return dart.as(this[_next], E);
+      }
+      get last() {
+        if (core.identical(this[_previous], this)) {
+          throw new core.StateError('No such element');
+        }
+        return dart.as(this[_previous], E);
+      }
+      get single() {
+        if (core.identical(this[_previous], this)) {
+          throw new core.StateError('No such element');
+        }
+        if (!dart.notNull(core.identical(this[_previous], this[_next]))) {
+          throw new core.StateError('Too many elements');
+        }
+        return dart.as(this[_next], E);
+      }
+      forEach(action) {
+        let modificationCount = this[_modificationCount];
+        let current = this[_next];
+        while (!dart.notNull(core.identical(current, this))) {
+          action(dart.as(current, E));
+          if (modificationCount !== this[_modificationCount]) {
+            throw new core.ConcurrentModificationError(this);
           }
-          cell = cell[_next];
+          current = current[_next];
+        }
+      }
+      get isEmpty() {
+        return this[_length] === 0;
+      }
+      [_insertAfter](entry, newEntry) {
+        if (newEntry.list !== null) {
+          throw new core.StateError('LinkedListEntry is already in a LinkedList');
         }
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        newEntry[_list] = this;
+        let predecessor = entry;
+        let successor = entry[_next];
+        successor[_previous] = newEntry;
+        newEntry[_previous] = predecessor;
+        newEntry[_next] = successor;
+        predecessor[_next] = newEntry;
+        this[_length] = dart.notNull(this[_length]) + 1;
+      }
+      [_unlink](entry) {
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        entry[_next][_previous] = entry[_previous];
+        entry[_previous][_next] = entry[_next];
+        this[_length] = dart.notNull(this[_length]) - 1;
+        entry[_list] = entry[_next] = entry[_previous] = null;
       }
     }
-    return LinkedHashMapKeyIterable;
+    return LinkedList;
   });
-  let LinkedHashMapKeyIterable = LinkedHashMapKeyIterable$(dynamic);
-  let _cell = Symbol('_cell');
-  let LinkedHashMapKeyIterator$ = dart.generic(function(E) {
-    class LinkedHashMapKeyIterator extends dart.Object {
-      LinkedHashMapKeyIterator($_map, $_modifications) {
-        this[_map] = $_map;
-        this[_modifications] = $_modifications;
-        this[_cell] = null;
+  let LinkedList = LinkedList$(dart.dynamic);
+  let _current = Symbol('_current');
+  let _LinkedListIterator$ = dart.generic(function(E) {
+    class _LinkedListIterator extends core.Object {
+      _LinkedListIterator(list) {
+        this[_list] = list;
+        this[_modificationCount] = list[_modificationCount];
+        this[_next] = list[_next];
         this[_current] = null;
-        this[_cell] = dart.as(dart.dload(this[_map], '_first'), LinkedHashMapCell);
       }
       get current() {
         return this[_current];
       }
       moveNext() {
-        if (this[_modifications] !== dart.dload(this[_map], '_modifications')) {
-          throw new core.ConcurrentModificationError(this[_map]);
-        } else if (this[_cell] === null) {
+        if (core.identical(this[_next], this[_list])) {
           this[_current] = null;
           return false;
-        } else {
-          this[_current] = dart.as(this[_cell][_key], E);
-          this[_cell] = this[_cell][_next];
-          return true;
         }
+        if (this[_modificationCount] !== this[_list][_modificationCount]) {
+          throw new core.ConcurrentModificationError(this);
+        }
+        this[_current] = dart.as(this[_next], E);
+        this[_next] = this[_next][_next];
+        return true;
       }
     }
-    return LinkedHashMapKeyIterator;
+    return _LinkedListIterator;
   });
-  let LinkedHashMapKeyIterator = LinkedHashMapKeyIterator$(dynamic);
-  let _elements = Symbol('_elements');
-  let _newSet = Symbol('_newSet');
-  let _computeElements = Symbol('_computeElements');
-  let _contains = Symbol('_contains');
-  let _lookup = Symbol('_lookup');
-  let _add = Symbol('_add');
-  let _isStringElement = Symbol('_isStringElement');
-  let _isNumericElement = Symbol('_isNumericElement');
-  let _HashSet$ = dart.generic(function(E) {
-    class _HashSet extends _HashSetBase$(E) {
-      _HashSet() {
-        this[_length] = 0;
-        this[_strings] = null;
-        this[_nums] = null;
-        this[_rest] = null;
-        this[_elements] = null;
-        super._HashSetBase();
+  let _LinkedListIterator = _LinkedListIterator$(dart.dynamic);
+  class _LinkedListLink extends core.Object {
+    _LinkedListLink() {
+      this[_next] = null;
+      this[_previous] = null;
+    }
+  }
+  let LinkedListEntry$ = dart.generic(function(E) {
+    class LinkedListEntry extends core.Object {
+      LinkedListEntry() {
+        this[_list] = null;
+        this[_next] = null;
+        this[_previous] = null;
       }
-      [_newSet]() {
-        return new _HashSet();
+      get list() {
+        return this[_list];
       }
-      get iterator() {
-        return new HashSetIterator(this, this[_computeElements]());
+      unlink() {
+        this[_list]._unlink(this);
       }
-      get length() {
-        return this[_length];
+      get next() {
+        if (core.identical(this[_next], this[_list]))
+          return null;
+        let result = dart.as(this[_next], E);
+        return result;
       }
-      get isEmpty() {
-        return this[_length] === 0;
+      get previous() {
+        if (core.identical(this[_previous], this[_list]))
+          return null;
+        return dart.as(this[_previous], E);
       }
-      get isNotEmpty() {
-        return !dart.notNull(this.isEmpty);
+      insertAfter(entry) {
+        this[_list]._insertAfter(this, entry);
       }
-      contains(object) {
-        if (_isStringElement(object)) {
-          let strings = this[_strings];
-          return strings === null ? false : _hasTableEntry(strings, object);
-        } else if (_isNumericElement(object)) {
-          let nums = this[_nums];
-          return nums === null ? false : _hasTableEntry(nums, object);
-        } else {
-          return this[_contains](object);
-        }
+      insertBefore(entry) {
+        this[_list]._insertAfter(this[_previous], entry);
       }
-      [_contains](object) {
-        let rest = this[_rest];
-        if (rest === null)
-          return false;
-        let bucket = this[_getBucket](rest, object);
-        return dart.notNull(this[_findBucketIndex](bucket, object)) >= 0;
+    }
+    return LinkedListEntry;
+  });
+  let LinkedListEntry = LinkedListEntry$(dart.dynamic);
+  let ListBase$ = dart.generic(function(E) {
+    class ListBase extends dart.mixin(core.Object, ListMixin$(E)) {
+      static listToString(list) {
+        return IterableBase.iterableToFullString(list, '[', ']');
       }
-      lookup(object) {
-        if (dart.notNull(_isStringElement(object)) || dart.notNull(_isNumericElement(object))) {
-          return dart.as(this.contains(object) ? object : null, E);
-        }
-        return this[_lookup](object);
+    }
+    return ListBase;
+  });
+  let ListBase = ListBase$(dart.dynamic);
+  let _filter = Symbol('_filter');
+  let ListMixin$ = dart.generic(function(E) {
+    class ListMixin extends core.Object {
+      get iterator() {
+        return new _internal.ListIterator(this);
       }
-      [_lookup](object) {
-        let rest = this[_rest];
-        if (rest === null)
-          return null;
-        let bucket = this[_getBucket](rest, object);
-        let index = this[_findBucketIndex](bucket, object);
-        if (dart.notNull(index) < 0)
-          return null;
-        return dart.as(bucket.get(index), E);
+      elementAt(index) {
+        return this.get(index);
       }
-      add(element) {
-        if (_isStringElement(element)) {
-          let strings = this[_strings];
-          if (strings === null)
-            this[_strings] = strings = _newHashTable();
-          return this[_addHashTableEntry](strings, element);
-        } else if (_isNumericElement(element)) {
-          let nums = this[_nums];
-          if (nums === null)
-            this[_nums] = nums = _newHashTable();
-          return this[_addHashTableEntry](nums, element);
-        } else {
-          return this[_add](element);
+      forEach(action) {
+        let length = this.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          action(this.get(i));
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
+          }
         }
       }
-      [_add](element) {
-        let rest = this[_rest];
-        if (rest === null)
-          this[_rest] = rest = _newHashTable();
-        let hash = this[_computeHashCode](element);
-        let bucket = rest[hash];
-        if (bucket === null) {
-          _setTableEntry(rest, hash, [element]);
-        } else {
-          let index = this[_findBucketIndex](bucket, element);
-          if (dart.notNull(index) >= 0)
-            return false;
-          bucket.push(element);
-        }
-        this[_length] = dart.notNull(this[_length]) + 1;
-        this[_elements] = null;
-        return true;
+      get isEmpty() {
+        return this.length === 0;
       }
-      addAll(objects) {
-        for (let each of objects) {
-          this.add(each);
-        }
+      get isNotEmpty() {
+        return !dart.notNull(this.isEmpty);
       }
-      remove(object) {
-        if (_isStringElement(object)) {
-          return this[_removeHashTableEntry](this[_strings], object);
-        } else if (_isNumericElement(object)) {
-          return this[_removeHashTableEntry](this[_nums], object);
-        } else {
-          return this[_remove](object);
+      get first() {
+        if (this.length === 0)
+          throw _internal.IterableElementError.noElement();
+        return this.get(0);
+      }
+      get last() {
+        if (this.length === 0)
+          throw _internal.IterableElementError.noElement();
+        return this.get(dart.notNull(this.length) - 1);
+      }
+      get single() {
+        if (this.length === 0)
+          throw _internal.IterableElementError.noElement();
+        if (dart.notNull(this.length) > 1)
+          throw _internal.IterableElementError.tooMany();
+        return this.get(0);
+      }
+      contains(element) {
+        let length = this.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
+          if (dart.equals(this.get(i), element))
+            return true;
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
+          }
         }
+        return false;
       }
-      [_remove](object) {
-        let rest = this[_rest];
-        if (rest === null)
-          return false;
-        let bucket = this[_getBucket](rest, object);
-        let index = this[_findBucketIndex](bucket, object);
-        if (dart.notNull(index) < 0)
-          return false;
-        this[_length] = dart.notNull(this[_length]) - 1;
-        this[_elements] = null;
-        bucket.splice(index, 1);
+      every(test) {
+        let length = this.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          if (!dart.notNull(test(this.get(i))))
+            return false;
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
+          }
+        }
         return true;
       }
-      clear() {
-        if (dart.notNull(this[_length]) > 0) {
-          this[_strings] = this[_nums] = this[_rest] = this[_elements] = null;
-          this[_length] = 0;
+      any(test) {
+        let length = this.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          if (test(this.get(i)))
+            return true;
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
+          }
         }
+        return false;
       }
-      [_computeElements]() {
-        if (this[_elements] !== null)
-          return this[_elements];
-        let result = new core.List(this[_length]);
-        let index = 0;
-        let strings = this[_strings];
-        if (strings !== null) {
-          let names = Object.getOwnPropertyNames(strings);
-          let entries = names.length;
-          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
-            let element = names[i];
-            result[index] = element;
-            index = dart.notNull(index) + 1;
+      firstWhere(test, opt$) {
+        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
+        let length = this.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let element = this.get(i);
+          if (test(element))
+            return element;
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
           }
         }
-        let nums = this[_nums];
-        if (nums !== null) {
-          let names = Object.getOwnPropertyNames(nums);
-          let entries = names.length;
-          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
-            let element = +names[i];
-            result[index] = element;
-            index = dart.notNull(index) + 1;
+        if (orElse !== null)
+          return orElse();
+        throw _internal.IterableElementError.noElement();
+      }
+      lastWhere(test, opt$) {
+        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
+        let length = this.length;
+        for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
+          let element = this.get(i);
+          if (test(element))
+            return element;
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
           }
         }
-        let rest = this[_rest];
-        if (rest !== null) {
-          let names = Object.getOwnPropertyNames(rest);
-          let entries = names.length;
-          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
-            let entry = names[i];
-            let bucket = rest[entry];
-            let length = bucket.length;
-            for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-              result[index] = bucket[i];
-              index = dart.notNull(index) + 1;
+        if (orElse !== null)
+          return orElse();
+        throw _internal.IterableElementError.noElement();
+      }
+      singleWhere(test) {
+        let length = this.length;
+        let match = null;
+        let matchFound = false;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let element = this.get(i);
+          if (test(element)) {
+            if (matchFound) {
+              throw _internal.IterableElementError.tooMany();
             }
+            matchFound = true;
+            match = element;
+          }
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
           }
         }
-        dart.assert(index === this[_length]);
-        return this[_elements] = result;
+        if (matchFound)
+          return match;
+        throw _internal.IterableElementError.noElement();
       }
-      [_addHashTableEntry](table, element) {
-        if (_hasTableEntry(table, element))
-          return false;
-        _setTableEntry(table, element, 0);
-        this[_length] = dart.notNull(this[_length]) + 1;
-        this[_elements] = null;
-        return true;
+      join(separator) {
+        if (separator === void 0)
+          separator = "";
+        if (this.length === 0)
+          return "";
+        let buffer = new core.StringBuffer();
+        buffer.writeAll(this, separator);
+        return buffer.toString();
       }
-      [_removeHashTableEntry](table, element) {
-        if (dart.notNull(table !== null) && dart.notNull(_hasTableEntry(table, element))) {
-          _deleteTableEntry(table, element);
-          this[_length] = dart.notNull(this[_length]) - 1;
-          this[_elements] = null;
-          return true;
-        } else {
-          return false;
-        }
+      where(test) {
+        return new _internal.WhereIterable(this, test);
       }
-      static [_isStringElement](element) {
-        return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
+      map(f) {
+        return new _internal.MappedListIterable(this, dart.as(f, dart.throw_("Unimplemented type (dynamic) → dynamic")));
       }
-      static [_isNumericElement](element) {
-        return dart.notNull(dart.is(element, core.num)) && (element & 0x3ffffff) === element;
+      expand(f) {
+        return new _internal.ExpandIterable(this, f);
       }
-      [_computeHashCode](element) {
-        return dart.dload(element, 'hashCode') & 0x3ffffff;
+      reduce(combine) {
+        let length = this.length;
+        if (length === 0)
+          throw _internal.IterableElementError.noElement();
+        let value = this.get(0);
+        for (let i = 1; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          value = combine(value, this.get(i));
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
+          }
+        }
+        return value;
       }
-      static [_hasTableEntry](table, key) {
-        let entry = table[key];
-        return entry !== null;
+      fold(initialValue, combine) {
+        let value = initialValue;
+        let length = this.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          value = combine(value, this.get(i));
+          if (length !== this.length) {
+            throw new core.ConcurrentModificationError(this);
+          }
+        }
+        return value;
       }
-      static [_setTableEntry](table, key, value) {
-        dart.assert(value !== null);
-        table[key] = value;
+      skip(count) {
+        return new _internal.SubListIterable(this, count, null);
       }
-      static [_deleteTableEntry](table, key) {
-        delete table[key];
+      skipWhile(test) {
+        return new _internal.SkipWhileIterable(this, test);
       }
-      [_getBucket](table, element) {
-        let hash = this[_computeHashCode](element);
-        return dart.as(table[hash], core.List);
+      take(count) {
+        return new _internal.SubListIterable(this, 0, count);
       }
-      [_findBucketIndex](bucket, element) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (dart.equals(bucket[i], element))
-            return i;
+      takeWhile(test) {
+        return new _internal.TakeWhileIterable(this, test);
+      }
+      toList(opt$) {
+        let growable = opt$.growable === void 0 ? true : opt$.growable;
+        let result = null;
+        if (growable) {
+          result = ((_) => {
+            _.length = this.length;
+            return _;
+          }).bind(this)(new core.List());
+        } else {
+          result = new core.List(this.length);
         }
-        return -1;
+        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
+          result.set(i, this.get(i));
+        }
+        return result;
       }
-      static [_newHashTable]() {
-        let table = Object.create(null);
-        let temporaryKey = '<non-identifier-key>';
-        _setTableEntry(table, temporaryKey, table);
-        _deleteTableEntry(table, temporaryKey);
-        return table;
+      toSet() {
+        let result = new core.Set();
+        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
+          result.add(this.get(i));
+        }
+        return result;
       }
-    }
-    return _HashSet;
-  });
-  let _HashSet = _HashSet$(dynamic);
-  let _IdentityHashSet$ = dart.generic(function(E) {
-    class _IdentityHashSet extends _HashSet$(E) {
-      [_newSet]() {
-        return new _IdentityHashSet();
+      add(element) {
+        this.set((($tmp) => this.length = dart.notNull($tmp) + 1, $tmp).bind(this)(this.length), element);
       }
-      [_computeHashCode](key) {
-        return core.identityHashCode(key) & 0x3ffffff;
+      addAll(iterable) {
+        for (let element of iterable) {
+          this.set((($tmp) => this.length = dart.notNull($tmp) + 1, $tmp).bind(this)(this.length), element);
+        }
       }
-      [_findBucketIndex](bucket, element) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (core.identical(bucket[i], element))
-            return i;
+      remove(element) {
+        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
+          if (dart.equals(this.get(i), element)) {
+            this.setRange(i, dart.notNull(this.length) - 1, this, dart.notNull(i) + 1);
+            this.length = 1;
+            return true;
+          }
         }
-        return -1;
+        return false;
       }
-    }
-    return _IdentityHashSet;
-  });
-  let _IdentityHashSet = _IdentityHashSet$(dynamic);
-  let _equality = Symbol('_equality');
-  let _hasher = Symbol('_hasher');
-  let _CustomHashSet$ = dart.generic(function(E) {
-    class _CustomHashSet extends _HashSet$(E) {
-      _CustomHashSet($_equality, $_hasher, validKey) {
-        this[_equality] = $_equality;
-        this[_hasher] = $_hasher;
-        this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
-        super._HashSet();
+      removeWhere(test) {
+        _filter(this, dart.as(test, dart.throw_("Unimplemented type (dynamic) → bool")), false);
       }
-      [_newSet]() {
-        return new _CustomHashSet(this[_equality], this[_hasher], this[_validKey]);
+      retainWhere(test) {
+        _filter(this, dart.as(test, dart.throw_("Unimplemented type (dynamic) → bool")), true);
       }
-      [_findBucketIndex](bucket, element) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
+      static [_filter](source, test, retainMatching) {
+        let retained = new List.from([]);
+        let length = source.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (this[_equality](dart.as(bucket[i], E), dart.as(element, E)))
-            return i;
+          let element = source.get(i);
+          if (test(element) === retainMatching) {
+            retained.add(element);
+          }
+          if (length !== source.length) {
+            throw new core.ConcurrentModificationError(source);
+          }
+        }
+        if (retained.length !== source.length) {
+          source.setRange(0, retained.length, retained);
+          source.length = retained.length;
         }
-        return -1;
       }
-      [_computeHashCode](element) {
-        return this[_hasher](dart.as(element, E)) & 0x3ffffff;
+      clear() {
+        this.length = 0;
       }
-      add(object) {
-        return super._add(object);
+      removeLast() {
+        if (this.length === 0) {
+          throw _internal.IterableElementError.noElement();
+        }
+        let result = this.get(dart.notNull(this.length) - 1);
+        this.length = dart.notNull(this.length) - 1;
+        return result;
       }
-      contains(object) {
-        if (!dart.notNull(this[_validKey](object)))
-          return false;
-        return super._contains(object);
+      sort(compare) {
+        if (compare === void 0)
+          compare = null;
+        if (compare === null) {
+          let defaultCompare = core.Comparable.compare;
+          compare = defaultCompare;
+        }
+        _internal.Sort.sort(this, dart.as(compare, dart.throw_("Unimplemented type (dynamic, dynamic) → int")));
       }
-      lookup(object) {
-        if (!dart.notNull(this[_validKey](object)))
-          return null;
-        return super._lookup(object);
+      shuffle(random) {
+        if (random === void 0)
+          random = null;
+        if (random === null)
+          random = new math.Random();
+        let length = this.length;
+        while (dart.notNull(length) > 1) {
+          let pos = random.nextInt(length);
+          length = 1;
+          let tmp = this.get(length);
+          this.set(length, this.get(pos));
+          this.set(pos, tmp);
+        }
       }
-      remove(object) {
-        if (!dart.notNull(this[_validKey](object)))
-          return false;
-        return super._remove(object);
+      asMap() {
+        return new _internal.ListMapView(this);
       }
-    }
-    return _CustomHashSet;
-  });
-  let _CustomHashSet = _CustomHashSet$(dynamic);
-  let HashSetIterator$ = dart.generic(function(E) {
-    class HashSetIterator extends dart.Object {
-      HashSetIterator($_set, $_elements) {
-        this[_set] = $_set;
-        this[_elements] = $_elements;
-        this[_offset] = 0;
-        this[_current] = null;
+      sublist(start, end) {
+        if (end === void 0)
+          end = null;
+        let listLength = this.length;
+        if (end === null)
+          end = listLength;
+        core.RangeError.checkValidRange(start, end, listLength);
+        let length = dart.notNull(end) - dart.notNull(start);
+        let result = new core.List();
+        result.length = length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          result.set(i, this.get(dart.notNull(start) + dart.notNull(i)));
+        }
+        return result;
       }
-      get current() {
-        return this[_current];
+      getRange(start, end) {
+        core.RangeError.checkValidRange(start, end, this.length);
+        return new _internal.SubListIterable(this, start, end);
       }
-      moveNext() {
-        let elements = this[_elements];
-        let offset = this[_offset];
-        if (elements !== dart.dload(this[_set], '_elements')) {
-          throw new core.ConcurrentModificationError(this[_set]);
-        } else if (dart.notNull(offset) >= elements.length) {
-          this[_current] = null;
-          return false;
-        } else {
-          this[_current] = dart.as(elements[offset], E);
-          this[_offset] = dart.notNull(offset) + 1;
-          return true;
+      removeRange(start, end) {
+        core.RangeError.checkValidRange(start, end, this.length);
+        let length = dart.notNull(end) - dart.notNull(start);
+        this.setRange(start, dart.notNull(this.length) - dart.notNull(length), this, end);
+        this.length = length;
+      }
+      fillRange(start, end, fill) {
+        if (fill === void 0)
+          fill = null;
+        core.RangeError.checkValidRange(start, end, this.length);
+        for (let i = start; dart.notNull(i) < dart.notNull(end); i = dart.notNull(i) + 1) {
+          this.set(i, fill);
         }
       }
-    }
-    return HashSetIterator;
-  });
-  let HashSetIterator = HashSetIterator$(dynamic);
-  let _unsupported = Symbol('_unsupported');
-  let _element = Symbol('_element');
-  let _filterWhere = Symbol('_filterWhere');
-  let _LinkedHashSet$ = dart.generic(function(E) {
-    class _LinkedHashSet extends _HashSetBase$(E) {
-      _LinkedHashSet() {
-        this[_length] = 0;
-        this[_strings] = null;
-        this[_nums] = null;
-        this[_rest] = null;
-        this[_first] = null;
-        this[_last] = null;
-        this[_modifications] = 0;
-        super._HashSetBase();
-      }
-      [_newSet]() {
-        return new _LinkedHashSet();
-      }
-      [_unsupported](operation) {
-        throw `LinkedHashSet: unsupported ${operation}`;
-      }
-      get iterator() {
-        return dart.as(new LinkedHashSetIterator(this, this[_modifications]), core.Iterator$(E));
-      }
-      get length() {
-        return this[_length];
-      }
-      get isEmpty() {
-        return this[_length] === 0;
-      }
-      get isNotEmpty() {
-        return !dart.notNull(this.isEmpty);
+      setRange(start, end, iterable, skipCount) {
+        if (skipCount === void 0)
+          skipCount = 0;
+        core.RangeError.checkValidRange(start, end, this.length);
+        let length = dart.notNull(end) - dart.notNull(start);
+        if (length === 0)
+          return;
+        core.RangeError.checkNotNegative(skipCount, "skipCount");
+        let otherList = null;
+        let otherStart = null;
+        if (dart.is(iterable, core.List)) {
+          otherList = dart.as(iterable, core.List);
+          otherStart = skipCount;
+        } else {
+          otherList = iterable.skip(skipCount).toList({growable: false});
+          otherStart = 0;
+        }
+        if (dart.notNull(otherStart) + dart.notNull(length) > dart.notNull(otherList.length)) {
+          throw _internal.IterableElementError.tooFew();
+        }
+        if (dart.notNull(otherStart) < dart.notNull(start)) {
+          for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
+            this.set(dart.notNull(start) + dart.notNull(i), dart.as(otherList.get(dart.notNull(otherStart) + dart.notNull(i)), E));
+          }
+        } else {
+          for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+            this.set(dart.notNull(start) + dart.notNull(i), dart.as(otherList.get(dart.notNull(otherStart) + dart.notNull(i)), E));
+          }
+        }
       }
-      contains(object) {
-        if (_isStringElement(object)) {
-          let strings = this[_strings];
-          if (strings === null)
-            return false;
-          let cell = dart.as(_getTableEntry(strings, object), LinkedHashSetCell);
-          return cell !== null;
-        } else if (_isNumericElement(object)) {
-          let nums = this[_nums];
-          if (nums === null)
-            return false;
-          let cell = dart.as(_getTableEntry(nums, object), LinkedHashSetCell);
-          return cell !== null;
+      replaceRange(start, end, newContents) {
+        core.RangeError.checkValidRange(start, end, this.length);
+        if (!dart.is(newContents, _internal.EfficientLength)) {
+          newContents = newContents.toList();
+        }
+        let removeLength = dart.notNull(end) - dart.notNull(start);
+        let insertLength = newContents.length;
+        if (dart.notNull(removeLength) >= dart.notNull(insertLength)) {
+          let delta = dart.notNull(removeLength) - dart.notNull(insertLength);
+          let insertEnd = dart.notNull(start) + dart.notNull(insertLength);
+          let newLength = dart.notNull(this.length) - dart.notNull(delta);
+          this.setRange(start, insertEnd, newContents);
+          if (delta !== 0) {
+            this.setRange(insertEnd, newLength, this, end);
+            this.length = newLength;
+          }
         } else {
-          return this[_contains](object);
+          let delta = dart.notNull(insertLength) - dart.notNull(removeLength);
+          let newLength = dart.notNull(this.length) + dart.notNull(delta);
+          let insertEnd = dart.notNull(start) + dart.notNull(insertLength);
+          this.length = newLength;
+          this.setRange(insertEnd, newLength, this, end);
+          this.setRange(start, insertEnd, newContents);
         }
       }
-      [_contains](object) {
-        let rest = this[_rest];
-        if (rest === null)
-          return false;
-        let bucket = this[_getBucket](rest, object);
-        return dart.notNull(this[_findBucketIndex](bucket, object)) >= 0;
+      indexOf(element, startIndex) {
+        if (startIndex === void 0)
+          startIndex = 0;
+        if (dart.notNull(startIndex) >= dart.notNull(this.length)) {
+          return -1;
+        }
+        if (dart.notNull(startIndex) < 0) {
+          startIndex = 0;
+        }
+        for (let i = startIndex; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
+          if (dart.equals(this.get(i), element)) {
+            return i;
+          }
+        }
+        return -1;
       }
-      lookup(object) {
-        if (dart.notNull(_isStringElement(object)) || dart.notNull(_isNumericElement(object))) {
-          return dart.as(this.contains(object) ? object : null, E);
+      lastIndexOf(element, startIndex) {
+        if (startIndex === void 0)
+          startIndex = null;
+        if (startIndex === null) {
+          startIndex = dart.notNull(this.length) - 1;
         } else {
-          return this[_lookup](object);
+          if (dart.notNull(startIndex) < 0) {
+            return -1;
+          }
+          if (dart.notNull(startIndex) >= dart.notNull(this.length)) {
+            startIndex = dart.notNull(this.length) - 1;
+          }
+        }
+        for (let i = startIndex; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
+          if (dart.equals(this.get(i), element)) {
+            return i;
+          }
         }
+        return -1;
       }
-      [_lookup](object) {
-        let rest = this[_rest];
-        if (rest === null)
-          return null;
-        let bucket = this[_getBucket](rest, object);
-        let index = this[_findBucketIndex](bucket, object);
-        if (dart.notNull(index) < 0)
-          return null;
-        return dart.as(dart.dload(bucket.get(index), '_element'), E);
+      insert(index, element) {
+        core.RangeError.checkValueInInterval(index, 0, this.length, "index");
+        if (index === this.length) {
+          this.add(element);
+          return;
+        }
+        if (!(typeof index == number))
+          throw new core.ArgumentError(index);
+        this.length = dart.notNull(this.length) + 1;
+        this.setRange(dart.notNull(index) + 1, this.length, this, index);
+        this.set(index, element);
       }
-      forEach(action) {
-        let cell = this[_first];
-        let modifications = this[_modifications];
-        while (cell !== null) {
-          action(dart.as(cell[_element], E));
-          if (modifications !== this[_modifications]) {
-            throw new core.ConcurrentModificationError(this);
+      removeAt(index) {
+        let result = this.get(index);
+        this.setRange(index, dart.notNull(this.length) - 1, this, dart.notNull(index) + 1);
+        this.length = dart.notNull(this.length) - 1;
+        return result;
+      }
+      insertAll(index, iterable) {
+        core.RangeError.checkValueInInterval(index, 0, this.length, "index");
+        if (dart.is(iterable, _internal.EfficientLength)) {
+          iterable = iterable.toList();
+        }
+        let insertionLength = iterable.length;
+        this.length = insertionLength;
+        this.setRange(dart.notNull(index) + dart.notNull(insertionLength), this.length, this, index);
+        this.setAll(index, iterable);
+      }
+      setAll(index, iterable) {
+        if (dart.is(iterable, core.List)) {
+          this.setRange(index, dart.notNull(index) + dart.notNull(iterable.length), iterable);
+        } else {
+          for (let element of iterable) {
+            this.set((($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index), element);
           }
-          cell = cell[_next];
         }
       }
-      get first() {
-        if (this[_first] === null)
-          throw new core.StateError("No elements");
-        return dart.as(this[_first][_element], E);
+      get reversed() {
+        return new _internal.ReversedListIterable(this);
       }
-      get last() {
-        if (this[_last] === null)
-          throw new core.StateError("No elements");
-        return dart.as(this[_last][_element], E);
+      toString() {
+        return IterableBase.iterableToFullString(this, '[', ']');
       }
-      add(element) {
-        if (_isStringElement(element)) {
-          let strings = this[_strings];
-          if (strings === null)
-            this[_strings] = strings = _newHashTable();
-          return this[_addHashTableEntry](strings, element);
-        } else if (_isNumericElement(element)) {
-          let nums = this[_nums];
-          if (nums === null)
-            this[_nums] = nums = _newHashTable();
-          return this[_addHashTableEntry](nums, element);
-        } else {
-          return this[_add](element);
+    }
+    return ListMixin;
+  });
+  let ListMixin = ListMixin$(dart.dynamic);
+  let MapBase$ = dart.generic(function(K, V) {
+    class MapBase extends dart.mixin(MapMixin$(K, V)) {
+    }
+    return MapBase;
+  });
+  let MapBase = MapBase$(dart.dynamic, dart.dynamic);
+  let MapMixin$ = dart.generic(function(K, V) {
+    class MapMixin extends core.Object {
+      forEach(action) {
+        for (let key of this.keys) {
+          action(key, this.get(key));
         }
       }
-      [_add](element) {
-        let rest = this[_rest];
-        if (rest === null)
-          this[_rest] = rest = _newHashTable();
-        let hash = this[_computeHashCode](element);
-        let bucket = rest[hash];
-        if (bucket === null) {
-          let cell = this[_newLinkedCell](element);
-          _setTableEntry(rest, hash, [cell]);
-        } else {
-          let index = this[_findBucketIndex](bucket, element);
-          if (dart.notNull(index) >= 0)
-            return false;
-          let cell = this[_newLinkedCell](element);
-          bucket.push(cell);
+      addAll(other) {
+        for (let key of other.keys) {
+          this.set(key, other.get(key));
         }
-        return true;
       }
-      remove(object) {
-        if (_isStringElement(object)) {
-          return this[_removeHashTableEntry](this[_strings], object);
-        } else if (_isNumericElement(object)) {
-          return this[_removeHashTableEntry](this[_nums], object);
-        } else {
-          return this[_remove](object);
+      containsValue(value) {
+        for (let key of this.keys) {
+          if (dart.equals(this.get(key), value))
+            return true;
         }
+        return false;
       }
-      [_remove](object) {
-        let rest = this[_rest];
-        if (rest === null)
-          return false;
-        let bucket = this[_getBucket](rest, object);
-        let index = this[_findBucketIndex](bucket, object);
-        if (dart.notNull(index) < 0)
-          return false;
-        let cell = dart.as(bucket.splice(index, 1)[0], LinkedHashSetCell);
-        this[_unlinkCell](cell);
-        return true;
-      }
-      removeWhere(test) {
-        this[_filterWhere](test, true);
+      putIfAbsent(key, ifAbsent) {
+        if (this.keys.contains(key)) {
+          return this.get(key);
+        }
+        return this.set(key, ifAbsent());
       }
-      retainWhere(test) {
-        this[_filterWhere](test, false);
+      containsKey(key) {
+        return this.keys.contains(key);
       }
-      [_filterWhere](test, removeMatching) {
-        let cell = this[_first];
-        while (cell !== null) {
-          let element = dart.as(cell[_element], E);
-          let next = cell[_next];
-          let modifications = this[_modifications];
-          let shouldRemove = removeMatching === test(element);
-          if (modifications !== this[_modifications]) {
-            throw new core.ConcurrentModificationError(this);
-          }
-          if (shouldRemove)
-            this.remove(element);
-          cell = next;
-        }
+      get length() {
+        return this.keys.length;
       }
-      clear() {
-        if (dart.notNull(this[_length]) > 0) {
-          this[_strings] = this[_nums] = this[_rest] = this[_first] = this[_last] = null;
-          this[_length] = 0;
-          this[_modified]();
-        }
+      get isEmpty() {
+        return this.keys.isEmpty;
       }
-      [_addHashTableEntry](table, element) {
-        let cell = dart.as(_getTableEntry(table, element), LinkedHashSetCell);
-        if (cell !== null)
-          return false;
-        _setTableEntry(table, element, this[_newLinkedCell](element));
-        return true;
+      get isNotEmpty() {
+        return this.keys.isNotEmpty;
       }
-      [_removeHashTableEntry](table, element) {
-        if (table === null)
-          return false;
-        let cell = dart.as(_getTableEntry(table, element), LinkedHashSetCell);
-        if (cell === null)
-          return false;
-        this[_unlinkCell](cell);
-        _deleteTableEntry(table, element);
-        return true;
+      get values() {
+        return new _MapBaseValueIterable(this);
       }
-      [_modified]() {
-        this[_modifications] = dart.notNull(this[_modifications]) + 1 & 67108863;
+      toString() {
+        return Maps.mapToString(this);
       }
-      [_newLinkedCell](element) {
-        let cell = new LinkedHashSetCell(element);
-        if (this[_first] === null) {
-          this[_first] = this[_last] = cell;
-        } else {
-          let last = this[_last];
-          cell[_previous] = last;
-          this[_last] = last[_next] = cell;
-        }
-        this[_length] = dart.notNull(this[_length]) + 1;
-        this[_modified]();
-        return cell;
+    }
+    return MapMixin;
+  });
+  let MapMixin = MapMixin$(dart.dynamic, dart.dynamic);
+  let UnmodifiableMapBase$ = dart.generic(function(K, V) {
+    class UnmodifiableMapBase extends dart.mixin(_UnmodifiableMapMixin$(K, V)) {
+    }
+    return UnmodifiableMapBase;
+  });
+  let UnmodifiableMapBase = UnmodifiableMapBase$(dart.dynamic, dart.dynamic);
+  let _map = Symbol('_map');
+  let _MapBaseValueIterable$ = dart.generic(function(V) {
+    class _MapBaseValueIterable extends IterableBase$(V) {
+      _MapBaseValueIterable($_map) {
+        this[_map] = $_map;
+        super.IterableBase();
       }
-      [_unlinkCell](cell) {
-        let previous = cell[_previous];
-        let next = cell[_next];
-        if (previous === null) {
-          dart.assert(dart.equals(cell, this[_first]));
-          this[_first] = next;
-        } else {
-          previous[_next] = next;
-        }
-        if (next === null) {
-          dart.assert(dart.equals(cell, this[_last]));
-          this[_last] = previous;
-        } else {
-          next[_previous] = previous;
-        }
-        this[_length] = dart.notNull(this[_length]) - 1;
-        this[_modified]();
+      get length() {
+        return this[_map].length;
       }
-      static [_isStringElement](element) {
-        return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
+      get isEmpty() {
+        return this[_map].isEmpty;
       }
-      static [_isNumericElement](element) {
-        return dart.notNull(dart.is(element, core.num)) && (element & 0x3ffffff) === element;
+      get isNotEmpty() {
+        return this[_map].isNotEmpty;
       }
-      [_computeHashCode](element) {
-        return dart.dload(element, 'hashCode') & 0x3ffffff;
+      get first() {
+        return dart.as(this[_map].get(this[_map].keys.first), V);
       }
-      static [_getTableEntry](table, key) {
-        return table[key];
+      get single() {
+        return dart.as(this[_map].get(this[_map].keys.single), V);
       }
-      static [_setTableEntry](table, key, value) {
-        dart.assert(value !== null);
-        table[key] = value;
+      get last() {
+        return dart.as(this[_map].get(this[_map].keys.last), V);
       }
-      static [_deleteTableEntry](table, key) {
-        delete table[key];
+      get iterator() {
+        return new _MapBaseValueIterator(this[_map]);
       }
-      [_getBucket](table, element) {
-        let hash = this[_computeHashCode](element);
-        return dart.as(table[hash], core.List);
+    }
+    return _MapBaseValueIterable;
+  });
+  let _MapBaseValueIterable = _MapBaseValueIterable$(dart.dynamic);
+  let _keys = Symbol('_keys');
+  let _MapBaseValueIterator$ = dart.generic(function(V) {
+    class _MapBaseValueIterator extends core.Object {
+      _MapBaseValueIterator(map) {
+        this[_map] = map;
+        this[_keys] = map.keys.iterator;
+        this[_current] = null;
       }
-      [_findBucketIndex](bucket, element) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (dart.equals(cell[_element], element))
-            return i;
+      moveNext() {
+        if (this[_keys].moveNext()) {
+          this[_current] = dart.as(this[_map].get(this[_keys].current), V);
+          return true;
         }
-        return -1;
+        this[_current] = null;
+        return false;
       }
-      static [_newHashTable]() {
-        let table = Object.create(null);
-        let temporaryKey = '<non-identifier-key>';
-        _setTableEntry(table, temporaryKey, table);
-        _deleteTableEntry(table, temporaryKey);
-        return table;
+      get current() {
+        return this[_current];
       }
     }
-    return _LinkedHashSet;
+    return _MapBaseValueIterator;
   });
-  let _LinkedHashSet = _LinkedHashSet$(dynamic);
-  let _LinkedIdentityHashSet$ = dart.generic(function(E) {
-    class _LinkedIdentityHashSet extends _LinkedHashSet$(E) {
-      [_newSet]() {
-        return new _LinkedIdentityHashSet();
+  let _MapBaseValueIterator = _MapBaseValueIterator$(dart.dynamic);
+  let _UnmodifiableMapMixin$ = dart.generic(function(K, V) {
+    class _UnmodifiableMapMixin extends core.Object {
+      set(key, value) {
+        throw new core.UnsupportedError("Cannot modify unmodifiable map");
       }
-      [_computeHashCode](key) {
-        return core.identityHashCode(key) & 0x3ffffff;
+      addAll(other) {
+        throw new core.UnsupportedError("Cannot modify unmodifiable map");
       }
-      [_findBucketIndex](bucket, element) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (core.identical(cell[_element], element))
-            return i;
-        }
-        return -1;
+      clear() {
+        throw new core.UnsupportedError("Cannot modify unmodifiable map");
+      }
+      remove(key) {
+        throw new core.UnsupportedError("Cannot modify unmodifiable map");
+      }
+      putIfAbsent(key, ifAbsent) {
+        throw new core.UnsupportedError("Cannot modify unmodifiable map");
       }
     }
-    return _LinkedIdentityHashSet;
+    return _UnmodifiableMapMixin;
   });
-  let _LinkedIdentityHashSet = _LinkedIdentityHashSet$(dynamic);
-  let _LinkedCustomHashSet$ = dart.generic(function(E) {
-    class _LinkedCustomHashSet extends _LinkedHashSet$(E) {
-      _LinkedCustomHashSet($_equality, $_hasher, validKey) {
-        this[_equality] = $_equality;
-        this[_hasher] = $_hasher;
-        this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
-        super._LinkedHashSet();
+  let _UnmodifiableMapMixin = _UnmodifiableMapMixin$(dart.dynamic, dart.dynamic);
+  let MapView$ = dart.generic(function(K, V) {
+    class MapView extends core.Object {
+      MapView(map) {
+        this[_map] = map;
       }
-      [_newSet]() {
-        return new _LinkedCustomHashSet(this[_equality], this[_hasher], this[_validKey]);
+      get(key) {
+        return this[_map].get(key);
       }
-      [_findBucketIndex](bucket, element) {
-        if (bucket === null)
-          return -1;
-        let length = bucket.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (this[_equality](dart.as(cell[_element], E), dart.as(element, E)))
-            return i;
-        }
-        return -1;
+      set(key, value) {
+        this[_map].set(key, value);
       }
-      [_computeHashCode](element) {
-        return this[_hasher](dart.as(element, E)) & 0x3ffffff;
+      addAll(other) {
+        this[_map].addAll(other);
       }
-      add(element) {
-        return super._add(element);
+      clear() {
+        this[_map].clear();
       }
-      contains(object) {
-        if (!dart.notNull(this[_validKey](object)))
-          return false;
-        return super._contains(object);
+      putIfAbsent(key, ifAbsent) {
+        return this[_map].putIfAbsent(key, ifAbsent);
       }
-      lookup(object) {
-        if (!dart.notNull(this[_validKey](object)))
-          return null;
-        return super._lookup(object);
+      containsKey(key) {
+        return this[_map].containsKey(key);
       }
-      remove(object) {
-        if (!dart.notNull(this[_validKey](object)))
-          return false;
-        return super._remove(object);
+      containsValue(value) {
+        return this[_map].containsValue(value);
       }
-      containsAll(elements) {
-        for (let element of elements) {
-          if (!dart.notNull(this[_validKey](element)) || !dart.notNull(this.contains(element)))
-            return false;
-        }
-        return true;
+      forEach(action) {
+        this[_map].forEach(action);
       }
-      removeAll(elements) {
-        for (let element of elements) {
-          if (this[_validKey](element)) {
-            super._remove(element);
-          }
-        }
+      get isEmpty() {
+        return this[_map].isEmpty;
+      }
+      get isNotEmpty() {
+        return this[_map].isNotEmpty;
+      }
+      get length() {
+        return this[_map].length;
+      }
+      get keys() {
+        return this[_map].keys;
+      }
+      remove(key) {
+        return this[_map].remove(key);
+      }
+      toString() {
+        return this[_map].toString();
+      }
+      get values() {
+        return this[_map].values;
       }
     }
-    return _LinkedCustomHashSet;
+    return MapView;
   });
-  let _LinkedCustomHashSet = _LinkedCustomHashSet$(dynamic);
-  class LinkedHashSetCell extends dart.Object {
-    LinkedHashSetCell($_element) {
-      this[_element] = $_element;
-      this[_next] = null;
-      this[_previous] = null;
+  let MapView = MapView$(dart.dynamic, dart.dynamic);
+  let UnmodifiableMapView$ = dart.generic(function(K, V) {
+    class UnmodifiableMapView extends dart.mixin(_UnmodifiableMapMixin$(K, V)) {
     }
-  }
-  let LinkedHashSetIterator$ = dart.generic(function(E) {
-    class LinkedHashSetIterator extends dart.Object {
-      LinkedHashSetIterator($_set, $_modifications) {
-        this[_set] = $_set;
-        this[_modifications] = $_modifications;
-        this[_cell] = null;
-        this[_current] = null;
-        this[_cell] = dart.as(dart.dload(this[_set], '_first'), LinkedHashSetCell);
-      }
-      get current() {
-        return this[_current];
+    return UnmodifiableMapView;
+  });
+  let UnmodifiableMapView = UnmodifiableMapView$(dart.dynamic, dart.dynamic);
+  let _toStringVisiting = Symbol('_toStringVisiting');
+  let _id = Symbol('_id');
+  let _fillMapWithMappedIterable = Symbol('_fillMapWithMappedIterable');
+  let _fillMapWithIterables = Symbol('_fillMapWithIterables');
+  class Maps extends core.Object {
+    static containsValue(map, value) {
+      for (let v of map.values) {
+        if (dart.equals(value, v)) {
+          return true;
+        }
       }
-      moveNext() {
-        if (this[_modifications] !== dart.dload(this[_set], '_modifications')) {
-          throw new core.ConcurrentModificationError(this[_set]);
-        } else if (this[_cell] === null) {
-          this[_current] = null;
-          return false;
-        } else {
-          this[_current] = dart.as(this[_cell][_element], E);
-          this[_cell] = this[_cell][_next];
+      return false;
+    }
+    static containsKey(map, key) {
+      for (let k of map.keys) {
+        if (dart.equals(key, k)) {
           return true;
         }
       }
+      return false;
     }
-    return LinkedHashSetIterator;
-  });
-  let LinkedHashSetIterator = LinkedHashSetIterator$(dynamic);
-  let _source = Symbol('_source');
-  let UnmodifiableListView$ = dart.generic(function(E) {
-    class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
-      UnmodifiableListView(source) {
-        this[_source] = source;
-        super.UnmodifiableListBase();
+    static putIfAbsent(map, key, ifAbsent) {
+      if (map.containsKey(key)) {
+        return map.get(key);
       }
-      get length() {
-        return this[_source].length;
+      let v = ifAbsent();
+      map.set(key, v);
+      return v;
+    }
+    static clear(map) {
+      for (let k of map.keys.toList()) {
+        map.remove(k);
       }
-      get(index) {
-        return this[_source].elementAt(index);
+    }
+    static forEach(map, f) {
+      for (let k of map.keys) {
+        f(k, map.get(k));
       }
     }
-    return UnmodifiableListView;
-  });
-  let UnmodifiableListView = UnmodifiableListView$(dynamic);
-  // Function _defaultEquals: (dynamic, dynamic) → bool
-  function _defaultEquals(a, b) {
-    return dart.equals(a, b);
-  }
-  // Function _defaultHashCode: (dynamic) → int
-  function _defaultHashCode(a) {
-    return dart.as(dart.dload(a, 'hashCode'), core.int);
-  }
-  let HashMap$ = dart.generic(function(K, V) {
-    class HashMap extends dart.Object {
-      HashMap(opt$) {
-        let equals = opt$.equals === void 0 ? null : opt$.equals;
-        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
-        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
-        if (isValidKey === null) {
-          if (hashCode === null) {
-            if (equals === null) {
-              return new _HashMap();
-            }
-            hashCode = _defaultHashCode;
-          } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
-              return new _IdentityHashMap();
-            }
-            if (equals === null) {
-              equals = _defaultEquals;
-            }
-          }
-        } else {
-          if (hashCode === null) {
-            hashCode = _defaultHashCode;
-          }
-          if (equals === null) {
-            equals = _defaultEquals;
-          }
-        }
-        return new _CustomHashMap(equals, hashCode, isValidKey);
+    static getValues(map) {
+      return map.keys.map((key) => map.get(key));
+    }
+    static length(map) {
+      return map.keys.length;
+    }
+    static isEmpty(map) {
+      return map.keys.isEmpty;
+    }
+    static isNotEmpty(map) {
+      return map.keys.isNotEmpty;
+    }
+    static mapToString(m) {
+      if (IterableBase._isToStringVisiting(m)) {
+        return '{...}';
       }
-      HashMap$identity() {
-        return new _IdentityHashMap();
+      let result = new core.StringBuffer();
+      try {
+        IterableBase[_toStringVisiting].add(m);
+        result.write('{');
+        let first = true;
+        m.forEach(((k, v) => {
+          if (!dart.notNull(first)) {
+            result.write(', ');
+          }
+          first = false;
+          result.write(k);
+          result.write(': ');
+          result.write(v);
+        }).bind(this));
+        result.write('}');
+      } finally {
+        dart.assert(core.identical(IterableBase[_toStringVisiting].last, m));
+        IterableBase[_toStringVisiting].removeLast();
       }
-      HashMap$from(other) {
-        let result = new HashMap();
-        other.forEach((k, v) => {
-          result.set(k, dart.as(v, V));
-        });
-        return result;
+      return result.toString();
+    }
+    static [_id](x) {
+      return x;
+    }
+    static [_fillMapWithMappedIterable](map, iterable, key, value) {
+      if (key === null)
+        key = _id;
+      if (value === null)
+        value = _id;
+      for (let element of iterable) {
+        map.set(key(element), value(element));
       }
-      HashMap$fromIterable(iterable, opt$) {
-        let key = opt$.key === void 0 ? null : opt$.key;
-        let value = opt$.value === void 0 ? null : opt$.value;
-        let map = new HashMap();
-        Maps._fillMapWithMappedIterable(map, iterable, key, value);
-        return map;
+    }
+    static [_fillMapWithIterables](map, keys, values) {
+      let keyIterator = keys.iterator;
+      let valueIterator = values.iterator;
+      let hasNextKey = keyIterator.moveNext();
+      let hasNextValue = valueIterator.moveNext();
+      while (dart.notNull(hasNextKey) && dart.notNull(hasNextValue)) {
+        map.set(keyIterator.current, valueIterator.current);
+        hasNextKey = keyIterator.moveNext();
+        hasNextValue = valueIterator.moveNext();
       }
-      HashMap$fromIterables(keys, values) {
-        let map = new HashMap();
-        Maps._fillMapWithIterables(map, keys, values);
-        return map;
+      if (dart.notNull(hasNextKey) || dart.notNull(hasNextValue)) {
+        throw new core.ArgumentError("Iterables do not have same length.");
       }
     }
-    dart.defineNamedConstructor(HashMap, 'identity');
-    dart.defineNamedConstructor(HashMap, 'from');
-    dart.defineNamedConstructor(HashMap, 'fromIterable');
-    dart.defineNamedConstructor(HashMap, 'fromIterables');
-    return HashMap;
-  });
-  let HashMap = HashMap$(dynamic, dynamic);
-  let _HashSetBase$ = dart.generic(function(E) {
-    class _HashSetBase extends SetBase$(E) {
-      difference(other) {
-        let result = this[_newSet]();
-        for (let element of this) {
-          if (!dart.notNull(other.contains(element)))
-            result.add(dart.as(element, E));
-        }
-        return result;
-      }
-      intersection(other) {
-        let result = this[_newSet]();
-        for (let element of this) {
-          if (other.contains(element))
-            result.add(dart.as(element, E));
-        }
-        return result;
+  }
+  let Queue$ = dart.generic(function(E) {
+    class Queue extends core.Object {
+      Queue() {
+        return new ListQueue();
       }
-      toSet() {
-        return ((_) => {
-          _.addAll(this);
-          return _;
-        }).bind(this)(this[_newSet]());
+      Queue$from(elements) {
+        return new ListQueue.from(elements);
       }
     }
-    return _HashSetBase;
+    dart.defineNamedConstructor(Queue, 'from');
+    return Queue;
   });
-  let _HashSetBase = _HashSetBase$(dynamic);
-  let HashSet$ = dart.generic(function(E) {
-    class HashSet extends dart.Object {
-      HashSet(opt$) {
-        let equals = opt$.equals === void 0 ? null : opt$.equals;
-        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
-        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
-        if (isValidKey === null) {
-          if (hashCode === null) {
-            if (equals === null) {
-              return new _HashSet();
-            }
-            hashCode = _defaultHashCode;
-          } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
-              return new _IdentityHashSet();
-            }
-            if (equals === null) {
-              equals = _defaultEquals;
-            }
-          }
-        } else {
-          if (hashCode === null) {
-            hashCode = _defaultHashCode;
-          }
-          if (equals === null) {
-            equals = _defaultEquals;
-          }
-        }
-        return new _CustomHashSet(equals, hashCode, isValidKey);
-      }
-      HashSet$identity() {
-        return new _IdentityHashSet();
+  let Queue = Queue$(dart.dynamic);
+  let _element = Symbol('_element');
+  let _link = Symbol('_link');
+  let _asNonSentinelEntry = Symbol('_asNonSentinelEntry');
+  let DoubleLinkedQueueEntry$ = dart.generic(function(E) {
+    class DoubleLinkedQueueEntry extends core.Object {
+      DoubleLinkedQueueEntry(e) {
+        this[_element] = e;
+        this[_previous] = null;
+        this[_next] = null;
       }
-      HashSet$from(elements) {
-        let result = new HashSet();
-        for (let e of elements)
-          result.add(e);
-        return result;
+      [_link](previous, next) {
+        this[_next] = next;
+        this[_previous] = previous;
+        previous[_next] = this;
+        next[_previous] = this;
       }
-    }
-    dart.defineNamedConstructor(HashSet, 'identity');
-    dart.defineNamedConstructor(HashSet, 'from');
-    return HashSet;
-  });
-  let HashSet = HashSet$(dynamic);
-  let IterableMixin$ = dart.generic(function(E) {
-    class IterableMixin extends dart.Object {
-      map(f) {
-        return new _internal.MappedIterable(this, f);
+      append(e) {
+        new DoubleLinkedQueueEntry(e)._link(this, this[_next]);
       }
-      where(f) {
-        return new _internal.WhereIterable(this, f);
+      prepend(e) {
+        new DoubleLinkedQueueEntry(e)._link(this[_previous], this);
       }
-      expand(f) {
-        return new _internal.ExpandIterable(this, f);
+      remove() {
+        this[_previous][_next] = this[_next];
+        this[_next][_previous] = this[_previous];
+        this[_next] = null;
+        this[_previous] = null;
+        return this[_element];
       }
-      contains(element) {
-        for (let e of this) {
-          if (dart.equals(e, element))
-            return true;
-        }
-        return false;
+      [_asNonSentinelEntry]() {
+        return this;
       }
-      forEach(f) {
-        for (let element of this)
-          f(element);
+      previousEntry() {
+        return this[_previous]._asNonSentinelEntry();
       }
-      reduce(combine) {
-        let iterator = this.iterator;
-        if (!dart.notNull(iterator.moveNext())) {
-          throw _internal.IterableElementError.noElement();
-        }
-        let value = iterator.current;
-        while (iterator.moveNext()) {
-          value = combine(value, iterator.current);
-        }
-        return value;
+      nextEntry() {
+        return this[_next]._asNonSentinelEntry();
       }
-      fold(initialValue, combine) {
-        let value = initialValue;
-        for (let element of this)
-          value = combine(value, element);
-        return value;
+      get element() {
+        return this[_element];
       }
-      every(f) {
-        for (let element of this) {
-          if (!dart.notNull(f(element)))
-            return false;
-        }
-        return true;
+      set element(e) {
+        this[_element] = e;
       }
-      join(separator) {
-        if (separator === void 0)
-          separator = "";
-        let iterator = this.iterator;
-        if (!dart.notNull(iterator.moveNext()))
-          return "";
-        let buffer = new core.StringBuffer();
-        if (dart.notNull(separator === null) || dart.notNull(dart.equals(separator, ""))) {
-          do {
-            buffer.write(`${iterator.current}`);
-          } while (iterator.moveNext());
-        } else {
-          buffer.write(`${iterator.current}`);
-          while (iterator.moveNext()) {
-            buffer.write(separator);
-            buffer.write(`${iterator.current}`);
-          }
-        }
-        return buffer.toString();
+    }
+    return DoubleLinkedQueueEntry;
+  });
+  let DoubleLinkedQueueEntry = DoubleLinkedQueueEntry$(dart.dynamic);
+  let _DoubleLinkedQueueEntrySentinel$ = dart.generic(function(E) {
+    class _DoubleLinkedQueueEntrySentinel extends DoubleLinkedQueueEntry$(E) {
+      _DoubleLinkedQueueEntrySentinel() {
+        super.DoubleLinkedQueueEntry(null);
+        this[_link](this, this);
       }
-      any(f) {
-        for (let element of this) {
-          if (f(element))
-            return true;
-        }
-        return false;
+      remove() {
+        throw _internal.IterableElementError.noElement();
       }
-      toList(opt$) {
-        let growable = opt$.growable === void 0 ? true : opt$.growable;
-        return new core.List.from(this, {growable: growable});
+      [_asNonSentinelEntry]() {
+        return null;
       }
-      toSet() {
-        return new core.Set.from(this);
+      set element(e) {
+        dart.assert(false);
       }
-      get length() {
-        dart.assert(!dart.is(this, _internal.EfficientLength));
-        let count = 0;
-        let it = this.iterator;
-        while (it.moveNext()) {
-          count = dart.notNull(count) + 1;
-        }
-        return count;
+      get element() {
+        throw _internal.IterableElementError.noElement();
       }
-      get isEmpty() {
-        return !dart.notNull(this.iterator.moveNext());
+    }
+    return _DoubleLinkedQueueEntrySentinel;
+  });
+  let _DoubleLinkedQueueEntrySentinel = _DoubleLinkedQueueEntrySentinel$(dart.dynamic);
+  let _sentinel = Symbol('_sentinel');
+  let _elementCount = Symbol('_elementCount');
+  let DoubleLinkedQueue$ = dart.generic(function(E) {
+    class DoubleLinkedQueue extends IterableBase$(E) {
+      DoubleLinkedQueue() {
+        this[_sentinel] = null;
+        this[_elementCount] = 0;
+        super.IterableBase();
+        this[_sentinel] = new _DoubleLinkedQueueEntrySentinel();
       }
-      get isNotEmpty() {
-        return !dart.notNull(this.isEmpty);
+      DoubleLinkedQueue$from(elements) {
+        let list = dart.as(new DoubleLinkedQueue(), Queue$(E));
+        for (let e of elements) {
+          list.addLast(e);
+        }
+        return dart.as(list, DoubleLinkedQueue$(E));
       }
-      take(n) {
-        return new _internal.TakeIterable(this, n);
+      get length() {
+        return this[_elementCount];
       }
-      takeWhile(test) {
-        return new _internal.TakeWhileIterable(this, test);
+      addLast(value) {
+        this[_sentinel].prepend(value);
+        this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
       }
-      skip(n) {
-        return new _internal.SkipIterable(this, n);
+      addFirst(value) {
+        this[_sentinel].append(value);
+        this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
       }
-      skipWhile(test) {
-        return new _internal.SkipWhileIterable(this, test);
+      add(value) {
+        this[_sentinel].prepend(value);
+        this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
       }
-      get first() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext())) {
-          throw _internal.IterableElementError.noElement();
+      addAll(iterable) {
+        for (let value of iterable) {
+          this[_sentinel].prepend(value);
+          this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
         }
-        return dart.as(it.current, E);
       }
-      get last() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext())) {
-          throw _internal.IterableElementError.noElement();
-        }
-        let result = null;
-        do {
-          result = dart.as(it.current, E);
-        } while (it.moveNext());
+      removeLast() {
+        let result = this[_sentinel][_previous].remove();
+        this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
         return result;
       }
-      get single() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext()))
-          throw _internal.IterableElementError.noElement();
-        let result = dart.as(it.current, E);
-        if (it.moveNext())
-          throw _internal.IterableElementError.tooMany();
+      removeFirst() {
+        let result = this[_sentinel][_next].remove();
+        this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
         return result;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        for (let element of this) {
-          if (test(element))
-            return element;
+      remove(o) {
+        let entry = this[_sentinel][_next];
+        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+          if (dart.equals(entry.element, o)) {
+            entry.remove();
+            this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
+            return true;
+          }
+          entry = entry[_next];
         }
-        if (orElse !== null)
-          return orElse();
-        throw _internal.IterableElementError.noElement();
+        return false;
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        let result = null;
-        let foundMatching = false;
-        for (let element of this) {
-          if (test(element)) {
-            result = element;
-            foundMatching = true;
+      [_filter](test, removeMatching) {
+        let entry = this[_sentinel][_next];
+        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+          let next = entry[_next];
+          if (core.identical(removeMatching, test(entry.element))) {
+            entry.remove();
+            this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
           }
+          entry = next;
         }
-        if (foundMatching)
-          return result;
-        if (orElse !== null)
-          return orElse();
-        throw _internal.IterableElementError.noElement();
       }
-      singleWhere(test) {
-        let result = null;
-        let foundMatching = false;
-        for (let element of this) {
-          if (test(element)) {
-            if (foundMatching) {
-              throw _internal.IterableElementError.tooMany();
-            }
-            result = element;
-            foundMatching = true;
-          }
-        }
-        if (foundMatching)
-          return result;
-        throw _internal.IterableElementError.noElement();
+      removeWhere(test) {
+        this[_filter](test, true);
       }
-      elementAt(index) {
-        if (!(typeof index == number))
-          throw new core.ArgumentError.notNull("index");
-        core.RangeError.checkNotNegative(index, "index");
-        let elementIndex = 0;
-        for (let element of this) {
-          if (index === elementIndex)
-            return element;
-          elementIndex = dart.notNull(elementIndex) + 1;
-        }
-        throw new core.RangeError.index(index, this, "index", null, elementIndex);
+      retainWhere(test) {
+        this[_filter](test, false);
       }
-      toString() {
-        return IterableBase.iterableToShortString(this, '(', ')');
+      get first() {
+        return this[_sentinel][_next].element;
       }
-    }
-    return IterableMixin;
-  });
-  let IterableMixin = IterableMixin$(dynamic);
-  let _isToStringVisiting = Symbol('_isToStringVisiting');
-  let _iterablePartsToStrings = Symbol('_iterablePartsToStrings');
-  let IterableBase$ = dart.generic(function(E) {
-    class IterableBase extends dart.Object {
-      IterableBase() {
+      get last() {
+        return this[_sentinel][_previous].element;
       }
-      map(f) {
-        return new _internal.MappedIterable(this, f);
+      get single() {
+        if (core.identical(this[_sentinel][_next], this[_sentinel][_previous])) {
+          return this[_sentinel][_next].element;
+        }
+        throw _internal.IterableElementError.tooMany();
       }
-      where(f) {
-        return new _internal.WhereIterable(this, f);
+      lastEntry() {
+        return this[_sentinel].previousEntry();
       }
-      expand(f) {
-        return new _internal.ExpandIterable(this, f);
+      firstEntry() {
+        return this[_sentinel].nextEntry();
       }
-      contains(element) {
-        for (let e of this) {
-          if (dart.equals(e, element))
-            return true;
-        }
-        return false;
+      get isEmpty() {
+        return core.identical(this[_sentinel][_next], this[_sentinel]);
       }
-      forEach(f) {
-        for (let element of this)
-          f(element);
+      clear() {
+        this[_sentinel][_next] = this[_sentinel];
+        this[_sentinel][_previous] = this[_sentinel];
+        this[_elementCount] = 0;
       }
-      reduce(combine) {
-        let iterator = this.iterator;
-        if (!dart.notNull(iterator.moveNext())) {
-          throw _internal.IterableElementError.noElement();
+      forEachEntry(f) {
+        let entry = this[_sentinel][_next];
+        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+          let nextEntry = entry[_next];
+          f(entry);
+          entry = nextEntry;
         }
-        let value = iterator.current;
-        while (iterator.moveNext()) {
-          value = combine(value, iterator.current);
+      }
+      get iterator() {
+        return new _DoubleLinkedQueueIterator(this[_sentinel]);
+      }
+      toString() {
+        return IterableBase.iterableToFullString(this, '{', '}');
+      }
+    }
+    dart.defineNamedConstructor(DoubleLinkedQueue, 'from');
+    return DoubleLinkedQueue;
+  });
+  let DoubleLinkedQueue = DoubleLinkedQueue$(dart.dynamic);
+  let _nextEntry = Symbol('_nextEntry');
+  let _DoubleLinkedQueueIterator$ = dart.generic(function(E) {
+    class _DoubleLinkedQueueIterator extends core.Object {
+      _DoubleLinkedQueueIterator(sentinel) {
+        this[_sentinel] = sentinel;
+        this[_nextEntry] = sentinel[_next];
+        this[_current] = null;
+      }
+      moveNext() {
+        if (!dart.notNull(core.identical(this[_nextEntry], this[_sentinel]))) {
+          this[_current] = this[_nextEntry][_element];
+          this[_nextEntry] = this[_nextEntry][_next];
+          return true;
         }
-        return value;
+        this[_current] = null;
+        this[_nextEntry] = this[_sentinel] = null;
+        return false;
       }
-      fold(initialValue, combine) {
-        let value = initialValue;
-        for (let element of this)
-          value = combine(value, element);
-        return value;
+      get current() {
+        return this[_current];
       }
-      every(f) {
-        for (let element of this) {
-          if (!dart.notNull(f(element)))
-            return false;
+    }
+    return _DoubleLinkedQueueIterator;
+  });
+  let _DoubleLinkedQueueIterator = _DoubleLinkedQueueIterator$(dart.dynamic);
+  let _head = Symbol('_head');
+  let _tail = Symbol('_tail');
+  let _table = Symbol('_table');
+  let _checkModification = Symbol('_checkModification');
+  let _writeToList = Symbol('_writeToList');
+  let _add = Symbol('_add');
+  let _preGrow = Symbol('_preGrow');
+  let _remove = Symbol('_remove');
+  let _filterWhere = Symbol('_filterWhere');
+  let _grow = Symbol('_grow');
+  let _isPowerOf2 = Symbol('_isPowerOf2');
+  let _nextPowerOf2 = Symbol('_nextPowerOf2');
+  let ListQueue$ = dart.generic(function(E) {
+    class ListQueue extends IterableBase$(E) {
+      ListQueue(initialCapacity) {
+        if (initialCapacity === void 0)
+          initialCapacity = null;
+        this[_head] = 0;
+        this[_tail] = 0;
+        this[_table] = null;
+        this[_modificationCount] = 0;
+        super.IterableBase();
+        if (initialCapacity === null || dart.notNull(initialCapacity) < dart.notNull(ListQueue._INITIAL_CAPACITY)) {
+          initialCapacity = ListQueue._INITIAL_CAPACITY;
+        } else if (!dart.notNull(_isPowerOf2(initialCapacity))) {
+          initialCapacity = _nextPowerOf2(initialCapacity);
         }
-        return true;
+        dart.assert(_isPowerOf2(initialCapacity));
+        this[_table] = new core.List(initialCapacity);
       }
-      join(separator) {
-        if (separator === void 0)
-          separator = "";
-        let iterator = this.iterator;
-        if (!dart.notNull(iterator.moveNext()))
-          return "";
-        let buffer = new core.StringBuffer();
-        if (dart.notNull(separator === null) || dart.notNull(dart.equals(separator, ""))) {
-          do {
-            buffer.write(`${iterator.current}`);
-          } while (iterator.moveNext());
+      ListQueue$from(elements) {
+        if (dart.is(elements, core.List)) {
+          let length = elements.length;
+          let queue = dart.as(new ListQueue(dart.notNull(length) + 1), ListQueue$(E));
+          dart.assert(dart.notNull(queue[_table].length) > dart.notNull(length));
+          let sourceList = elements;
+          queue[_table].setRange(0, length, dart.as(sourceList, core.Iterable$(E)), 0);
+          queue[_tail] = length;
+          return queue;
         } else {
-          buffer.write(`${iterator.current}`);
-          while (iterator.moveNext()) {
-            buffer.write(separator);
-            buffer.write(`${iterator.current}`);
+          let capacity = ListQueue._INITIAL_CAPACITY;
+          if (dart.is(elements, _internal.EfficientLength)) {
+            capacity = elements.length;
           }
+          let result = new ListQueue(capacity);
+          for (let element of elements) {
+            result.addLast(element);
+          }
+          return result;
         }
-        return buffer.toString();
-      }
-      any(f) {
-        for (let element of this) {
-          if (f(element))
-            return true;
-        }
-        return false;
       }
-      toList(opt$) {
-        let growable = opt$.growable === void 0 ? true : opt$.growable;
-        return new core.List.from(this, {growable: growable});
-      }
-      toSet() {
-        return new core.Set.from(this);
+      get iterator() {
+        return new _ListQueueIterator(this);
       }
-      get length() {
-        dart.assert(!dart.is(this, _internal.EfficientLength));
-        let count = 0;
-        let it = this.iterator;
-        while (it.moveNext()) {
-          count = dart.notNull(count) + 1;
+      forEach(action) {
+        let modificationCount = this[_modificationCount];
+        for (let i = this[_head]; i !== this[_tail]; i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1) {
+          action(this[_table].get(i));
+          this[_checkModification](modificationCount);
         }
-        return count;
       }
       get isEmpty() {
-        return !dart.notNull(this.iterator.moveNext());
+        return this[_head] === this[_tail];
       }
-      get isNotEmpty() {
-        return !dart.notNull(this.isEmpty);
+      get length() {
+        return dart.notNull(this[_tail]) - dart.notNull(this[_head]) & dart.notNull(this[_table].length) - 1;
       }
-      take(n) {
-        return new _internal.TakeIterable(this, n);
+      get first() {
+        if (this[_head] === this[_tail])
+          throw _internal.IterableElementError.noElement();
+        return this[_table].get(this[_head]);
       }
-      takeWhile(test) {
-        return new _internal.TakeWhileIterable(this, test);
-      }
-      skip(n) {
-        return new _internal.SkipIterable(this, n);
-      }
-      skipWhile(test) {
-        return new _internal.SkipWhileIterable(this, test);
-      }
-      get first() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext())) {
-          throw _internal.IterableElementError.noElement();
-        }
-        return dart.as(it.current, E);
-      }
-      get last() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext())) {
-          throw _internal.IterableElementError.noElement();
-        }
-        let result = null;
-        do {
-          result = dart.as(it.current, E);
-        } while (it.moveNext());
-        return result;
+      get last() {
+        if (this[_head] === this[_tail])
+          throw _internal.IterableElementError.noElement();
+        return this[_table].get(dart.notNull(this[_tail]) - 1 & dart.notNull(this[_table].length) - 1);
       }
       get single() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext()))
+        if (this[_head] === this[_tail])
           throw _internal.IterableElementError.noElement();
-        let result = dart.as(it.current, E);
-        if (it.moveNext())
+        if (dart.notNull(this.length) > 1)
           throw _internal.IterableElementError.tooMany();
-        return result;
+        return this[_table].get(this[_head]);
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        for (let element of this) {
-          if (test(element))
-            return element;
+      elementAt(index) {
+        core.RangeError.checkValidIndex(index, this);
+        return this[_table].get(dart.notNull(this[_head]) + dart.notNull(index) & dart.notNull(this[_table].length) - 1);
+      }
+      toList(opt$) {
+        let growable = opt$.growable === void 0 ? true : opt$.growable;
+        let list = null;
+        if (growable) {
+          list = ((_) => {
+            _.length = this.length;
+            return _;
+          }).bind(this)(new core.List());
+        } else {
+          list = new core.List(this.length);
         }
-        if (orElse !== null)
-          return orElse();
-        throw _internal.IterableElementError.noElement();
+        this[_writeToList](list);
+        return list;
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        let result = null;
-        let foundMatching = false;
-        for (let element of this) {
-          if (test(element)) {
-            result = element;
-            foundMatching = true;
+      add(element) {
+        this[_add](element);
+      }
+      addAll(elements) {
+        if (dart.is(elements, core.List)) {
+          let list = dart.as(elements, core.List);
+          let addCount = list.length;
+          let length = this.length;
+          if (dart.notNull(length) + dart.notNull(addCount) >= dart.notNull(this[_table].length)) {
+            this[_preGrow](dart.notNull(length) + dart.notNull(addCount));
+            this[_table].setRange(length, dart.notNull(length) + dart.notNull(addCount), dart.as(list, core.Iterable$(E)), 0);
+            this[_tail] = addCount;
+          } else {
+            let endSpace = dart.notNull(this[_table].length) - dart.notNull(this[_tail]);
+            if (dart.notNull(addCount) < dart.notNull(endSpace)) {
+              this[_table].setRange(this[_tail], dart.notNull(this[_tail]) + dart.notNull(addCount), dart.as(list, core.Iterable$(E)), 0);
+              this[_tail] = addCount;
+            } else {
+              let preSpace = dart.notNull(addCount) - dart.notNull(endSpace);
+              this[_table].setRange(this[_tail], dart.notNull(this[_tail]) + dart.notNull(endSpace), dart.as(list, core.Iterable$(E)), 0);
+              this[_table].setRange(0, preSpace, dart.as(list, core.Iterable$(E)), endSpace);
+              this[_tail] = preSpace;
+            }
           }
+          this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        } else {
+          for (let element of elements)
+            this[_add](element);
         }
-        if (foundMatching)
-          return result;
-        if (orElse !== null)
-          return orElse();
-        throw _internal.IterableElementError.noElement();
       }
-      singleWhere(test) {
-        let result = null;
-        let foundMatching = false;
-        for (let element of this) {
-          if (test(element)) {
-            if (foundMatching) {
-              throw _internal.IterableElementError.tooMany();
-            }
-            result = element;
-            foundMatching = true;
+      remove(object) {
+        for (let i = this[_head]; i !== this[_tail]; i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1) {
+          let element = this[_table].get(i);
+          if (dart.equals(element, object)) {
+            this[_remove](i);
+            this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+            return true;
           }
         }
-        if (foundMatching)
-          return result;
-        throw _internal.IterableElementError.noElement();
+        return false;
       }
-      elementAt(index) {
-        if (!(typeof index == number))
-          throw new core.ArgumentError.notNull("index");
-        core.RangeError.checkNotNegative(index, "index");
-        let elementIndex = 0;
-        for (let element of this) {
-          if (index === elementIndex)
-            return element;
-          elementIndex = dart.notNull(elementIndex) + 1;
+      [_filterWhere](test, removeMatching) {
+        let index = this[_head];
+        let modificationCount = this[_modificationCount];
+        let i = this[_head];
+        while (i !== this[_tail]) {
+          let element = this[_table].get(i);
+          let remove = core.identical(removeMatching, test(element));
+          this[_checkModification](modificationCount);
+          if (remove) {
+            i = this[_remove](i);
+            modificationCount = this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+          } else {
+            i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1;
+          }
         }
-        throw new core.RangeError.index(index, this, "index", null, elementIndex);
       }
-      toString() {
-        return iterableToShortString(this, '(', ')');
+      removeWhere(test) {
+        this[_filterWhere](test, true);
       }
-      static iterableToShortString(iterable, leftDelimiter, rightDelimiter) {
-        if (leftDelimiter === void 0)
-          leftDelimiter = '(';
-        if (rightDelimiter === void 0)
-          rightDelimiter = ')';
-        if (_isToStringVisiting(iterable)) {
-          if (dart.notNull(dart.equals(leftDelimiter, "(")) && dart.notNull(dart.equals(rightDelimiter, ")"))) {
-            return "(...)";
+      retainWhere(test) {
+        this[_filterWhere](test, false);
+      }
+      clear() {
+        if (this[_head] !== this[_tail]) {
+          for (let i = this[_head]; i !== this[_tail]; i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1) {
+            this[_table].set(i, null);
           }
-          return `${leftDelimiter}...${rightDelimiter}`;
-        }
-        let parts = new List.from([]);
-        _toStringVisiting.add(iterable);
-        try {
-          _iterablePartsToStrings(iterable, parts);
-        } finally {
-          dart.assert(core.identical(_toStringVisiting.last, iterable));
-          _toStringVisiting.removeLast();
+          this[_head] = this[_tail] = 0;
+          this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
         }
-        return ((_) => {
-          _.writeAll(parts, ", ");
-          _.write(rightDelimiter);
-          return _;
-        }).bind(this)(new core.StringBuffer(leftDelimiter)).toString();
       }
-      static iterableToFullString(iterable, leftDelimiter, rightDelimiter) {
-        if (leftDelimiter === void 0)
-          leftDelimiter = '(';
-        if (rightDelimiter === void 0)
-          rightDelimiter = ')';
-        if (_isToStringVisiting(iterable)) {
-          return `${leftDelimiter}...${rightDelimiter}`;
-        }
-        let buffer = new core.StringBuffer(leftDelimiter);
-        _toStringVisiting.add(iterable);
-        try {
-          buffer.writeAll(iterable, ", ");
-        } finally {
-          dart.assert(core.identical(_toStringVisiting.last, iterable));
-          _toStringVisiting.removeLast();
+      toString() {
+        return IterableBase.iterableToFullString(this, "{", "}");
+      }
+      addLast(element) {
+        this[_add](element);
+      }
+      addFirst(element) {
+        this[_head] = dart.notNull(this[_head]) - 1 & dart.notNull(this[_table].length) - 1;
+        this[_table].set(this[_head], element);
+        if (this[_head] === this[_tail])
+          this[_grow]();
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+      }
+      removeFirst() {
+        if (this[_head] === this[_tail])
+          throw _internal.IterableElementError.noElement();
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        let result = this[_table].get(this[_head]);
+        this[_table].set(this[_head], null);
+        this[_head] = dart.notNull(this[_head]) + 1 & dart.notNull(this[_table].length) - 1;
+        return result;
+      }
+      removeLast() {
+        if (this[_head] === this[_tail])
+          throw _internal.IterableElementError.noElement();
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        this[_tail] = dart.notNull(this[_tail]) - 1 & dart.notNull(this[_table].length) - 1;
+        let result = this[_table].get(this[_tail]);
+        this[_table].set(this[_tail], null);
+        return result;
+      }
+      static [_isPowerOf2](number) {
+        return (dart.notNull(number) & dart.notNull(number) - 1) === 0;
+      }
+      static [_nextPowerOf2](number) {
+        dart.assert(dart.notNull(number) > 0);
+        number = (dart.notNull(number) << 1) - 1;
+        for (;;) {
+          let nextNumber = dart.notNull(number) & dart.notNull(number) - 1;
+          if (nextNumber === 0)
+            return number;
+          number = nextNumber;
         }
-        buffer.write(rightDelimiter);
-        return buffer.toString();
       }
-      static [_isToStringVisiting](o) {
-        for (let i = 0; dart.notNull(i) < dart.notNull(_toStringVisiting.length); i = dart.notNull(i) + 1) {
-          if (core.identical(o, _toStringVisiting.get(i)))
-            return true;
+      [_checkModification](expectedModificationCount) {
+        if (expectedModificationCount !== this[_modificationCount]) {
+          throw new core.ConcurrentModificationError(this);
         }
-        return false;
       }
-      static [_iterablePartsToStrings](iterable, parts) {
-        let LENGTH_LIMIT = 80;
-        let HEAD_COUNT = 3;
-        let TAIL_COUNT = 2;
-        let MAX_COUNT = 100;
-        let OVERHEAD = 2;
-        let ELLIPSIS_SIZE = 3;
-        let length = 0;
-        let count = 0;
-        let it = iterable.iterator;
-        while (dart.notNull(length) < dart.notNull(LENGTH_LIMIT) || dart.notNull(count) < dart.notNull(HEAD_COUNT)) {
-          if (!dart.notNull(it.moveNext()))
-            return;
-          let next = `${it.current}`;
-          parts.add(next);
-          length = dart.notNull(next.length) + dart.notNull(OVERHEAD);
-          count = dart.notNull(count) + 1;
-        }
-        let penultimateString = null;
-        let ultimateString = null;
-        let penultimate = null;
-        let ultimate = null;
-        if (!dart.notNull(it.moveNext())) {
-          if (dart.notNull(count) <= dart.notNull(HEAD_COUNT) + dart.notNull(TAIL_COUNT))
-            return;
-          ultimateString = dart.as(parts.removeLast(), core.String);
-          penultimateString = dart.as(parts.removeLast(), core.String);
-        } else {
-          penultimate = it.current;
-          count = dart.notNull(count) + 1;
-          if (!dart.notNull(it.moveNext())) {
-            if (dart.notNull(count) <= dart.notNull(HEAD_COUNT) + 1) {
-              parts.add(`${penultimate}`);
-              return;
-            }
-            ultimateString = `${penultimate}`;
-            penultimateString = dart.as(parts.removeLast(), core.String);
-            length = dart.notNull(ultimateString.length) + dart.notNull(OVERHEAD);
-          } else {
-            ultimate = it.current;
-            count = dart.notNull(count) + 1;
-            dart.assert(dart.notNull(count) < dart.notNull(MAX_COUNT));
-            while (it.moveNext()) {
-              penultimate = ultimate;
-              ultimate = it.current;
-              count = dart.notNull(count) + 1;
-              if (dart.notNull(count) > dart.notNull(MAX_COUNT)) {
-                while (dart.notNull(length) > dart.notNull(LENGTH_LIMIT) - dart.notNull(ELLIPSIS_SIZE) - dart.notNull(OVERHEAD) && dart.notNull(count) > dart.notNull(HEAD_COUNT)) {
-                  length = dart.as(dart.dbinary(dart.dload(parts.removeLast(), 'length'), '+', OVERHEAD), core.int);
-                  count = dart.notNull(count) - 1;
-                }
-                parts.add("...");
-                return;
-              }
-            }
-            penultimateString = `${penultimate}`;
-            ultimateString = `${ultimate}`;
-            length = dart.notNull(ultimateString.length) + dart.notNull(penultimateString.length) + 2 * dart.notNull(OVERHEAD);
+      [_add](element) {
+        this[_table].set(this[_tail], element);
+        this[_tail] = dart.notNull(this[_tail]) + 1 & dart.notNull(this[_table].length) - 1;
+        if (this[_head] === this[_tail])
+          this[_grow]();
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+      }
+      [_remove](offset) {
+        let mask = dart.notNull(this[_table].length) - 1;
+        let startDistance = dart.notNull(offset) - dart.notNull(this[_head]) & dart.notNull(mask);
+        let endDistance = dart.notNull(this[_tail]) - dart.notNull(offset) & dart.notNull(mask);
+        if (dart.notNull(startDistance) < dart.notNull(endDistance)) {
+          let i = offset;
+          while (i !== this[_head]) {
+            let prevOffset = dart.notNull(i) - 1 & dart.notNull(mask);
+            this[_table].set(i, this[_table].get(prevOffset));
+            i = prevOffset;
           }
-        }
-        let elision = null;
-        if (dart.notNull(count) > dart.notNull(parts.length) + dart.notNull(TAIL_COUNT)) {
-          elision = "...";
-          length = dart.notNull(ELLIPSIS_SIZE) + dart.notNull(OVERHEAD);
-        }
-        while (dart.notNull(length) > dart.notNull(LENGTH_LIMIT) && dart.notNull(parts.length) > dart.notNull(HEAD_COUNT)) {
-          length = dart.as(dart.dbinary(dart.dload(parts.removeLast(), 'length'), '+', OVERHEAD), core.int);
-          if (elision === null) {
-            elision = "...";
-            length = dart.notNull(ELLIPSIS_SIZE) + dart.notNull(OVERHEAD);
+          this[_table].set(this[_head], null);
+          this[_head] = dart.notNull(this[_head]) + 1 & dart.notNull(mask);
+          return dart.notNull(offset) + 1 & dart.notNull(mask);
+        } else {
+          this[_tail] = dart.notNull(this[_tail]) - 1 & dart.notNull(mask);
+          let i = offset;
+          while (i !== this[_tail]) {
+            let nextOffset = dart.notNull(i) + 1 & dart.notNull(mask);
+            this[_table].set(i, this[_table].get(nextOffset));
+            i = nextOffset;
           }
+          this[_table].set(this[_tail], null);
+          return offset;
         }
-        if (elision !== null) {
-          parts.add(elision);
+      }
+      [_grow]() {
+        let newTable = new core.List(dart.notNull(this[_table].length) * 2);
+        let split = dart.notNull(this[_table].length) - dart.notNull(this[_head]);
+        newTable.setRange(0, split, this[_table], this[_head]);
+        newTable.setRange(split, dart.notNull(split) + dart.notNull(this[_head]), this[_table], 0);
+        this[_head] = 0;
+        this[_tail] = this[_table].length;
+        this[_table] = newTable;
+      }
+      [_writeToList](target) {
+        dart.assert(dart.notNull(target.length) >= dart.notNull(this.length));
+        if (dart.notNull(this[_head]) <= dart.notNull(this[_tail])) {
+          let length = dart.notNull(this[_tail]) - dart.notNull(this[_head]);
+          target.setRange(0, length, this[_table], this[_head]);
+          return length;
+        } else {
+          let firstPartSize = dart.notNull(this[_table].length) - dart.notNull(this[_head]);
+          target.setRange(0, firstPartSize, this[_table], this[_head]);
+          target.setRange(firstPartSize, dart.notNull(firstPartSize) + dart.notNull(this[_tail]), this[_table], 0);
+          return dart.notNull(this[_tail]) + dart.notNull(firstPartSize);
         }
-        parts.add(penultimateString);
-        parts.add(ultimateString);
       }
-    }
-    dart.defineLazyProperties(IterableBase, {
-      get _toStringVisiting() {
-        return new List.from([]);
+      [_preGrow](newElementCount) {
+        dart.assert(dart.notNull(newElementCount) >= dart.notNull(this.length));
+        newElementCount = dart.notNull(newElementCount) >> 1;
+        let newCapacity = _nextPowerOf2(newElementCount);
+        let newTable = new core.List(newCapacity);
+        this[_tail] = this[_writeToList](newTable);
+        this[_table] = newTable;
+        this[_head] = 0;
       }
-    });
-    return IterableBase;
+    }
+    dart.defineNamedConstructor(ListQueue, 'from');
+    ListQueue._INITIAL_CAPACITY = 8;
+    return ListQueue;
   });
-  let IterableBase = IterableBase$(dynamic);
-  let _iterator = Symbol('_iterator');
-  let _state = Symbol('_state');
-  let _move = Symbol('_move');
-  let HasNextIterator$ = dart.generic(function(E) {
-    class HasNextIterator extends dart.Object {
-      HasNextIterator($_iterator) {
-        this[_iterator] = $_iterator;
-        this[_state] = _NOT_MOVED_YET;
-      }
-      get hasNext() {
-        if (this[_state] === _NOT_MOVED_YET)
-          this[_move]();
-        return this[_state] === _HAS_NEXT_AND_NEXT_IN_CURRENT;
+  let ListQueue = ListQueue$(dart.dynamic);
+  let _queue = Symbol('_queue');
+  let _end = Symbol('_end');
+  let _position = Symbol('_position');
+  let _ListQueueIterator$ = dart.generic(function(E) {
+    class _ListQueueIterator extends core.Object {
+      _ListQueueIterator(queue) {
+        this[_queue] = queue;
+        this[_end] = queue[_tail];
+        this[_modificationCount] = queue[_modificationCount];
+        this[_position] = queue[_head];
+        this[_current] = null;
       }
-      next() {
-        if (!dart.notNull(this.hasNext))
-          throw new core.StateError("No more elements");
-        dart.assert(this[_state] === _HAS_NEXT_AND_NEXT_IN_CURRENT);
-        let result = dart.as(this[_iterator].current, E);
-        this[_move]();
-        return result;
+      get current() {
+        return this[_current];
       }
-      [_move]() {
-        if (this[_iterator].moveNext()) {
-          this[_state] = _HAS_NEXT_AND_NEXT_IN_CURRENT;
-        } else {
-          this[_state] = _NO_NEXT;
+      moveNext() {
+        this[_queue]._checkModification(this[_modificationCount]);
+        if (this[_position] === this[_end]) {
+          this[_current] = null;
+          return false;
         }
+        this[_current] = dart.as(this[_queue][_table].get(this[_position]), E);
+        this[_position] = dart.notNull(this[_position]) + 1 & dart.notNull(this[_queue][_table].length) - 1;
+        return true;
       }
     }
-    HasNextIterator._HAS_NEXT_AND_NEXT_IN_CURRENT = 0;
-    HasNextIterator._NO_NEXT = 1;
-    HasNextIterator._NOT_MOVED_YET = 2;
-    return HasNextIterator;
+    return _ListQueueIterator;
   });
-  let HasNextIterator = HasNextIterator$(dynamic);
-  let LinkedHashMap$ = dart.generic(function(K, V) {
-    class LinkedHashMap extends dart.Object {
-      LinkedHashMap(opt$) {
-        let equals = opt$.equals === void 0 ? null : opt$.equals;
-        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
-        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
-        if (isValidKey === null) {
-          if (hashCode === null) {
-            if (equals === null) {
-              return new _LinkedHashMap();
-            }
-            hashCode = _defaultHashCode;
-          } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
-              return new _LinkedIdentityHashMap();
-            }
-            if (equals === null) {
-              equals = _defaultEquals;
-            }
-          }
-        } else {
-          if (hashCode === null) {
-            hashCode = _defaultHashCode;
-          }
-          if (equals === null) {
-            equals = _defaultEquals;
-          }
-        }
-        return new _LinkedCustomHashMap(equals, hashCode, isValidKey);
+  let _ListQueueIterator = _ListQueueIterator$(dart.dynamic);
+  let SetMixin$ = dart.generic(function(E) {
+    class SetMixin extends core.Object {
+      get isEmpty() {
+        return this.length === 0;
       }
-      LinkedHashMap$identity() {
-        return new _LinkedIdentityHashMap();
+      get isNotEmpty() {
+        return this.length !== 0;
       }
-      LinkedHashMap$from(other) {
-        let result = new LinkedHashMap();
-        other.forEach((k, v) => {
-          result.set(k, dart.as(v, V));
-        });
-        return result;
+      clear() {
+        this.removeAll(this.toList());
       }
-      LinkedHashMap$fromIterable(iterable, opt$) {
-        let key = opt$.key === void 0 ? null : opt$.key;
-        let value = opt$.value === void 0 ? null : opt$.value;
-        let map = new LinkedHashMap();
-        Maps._fillMapWithMappedIterable(map, iterable, key, value);
-        return map;
+      addAll(elements) {
+        for (let element of elements)
+          this.add(element);
       }
-      LinkedHashMap$fromIterables(keys, values) {
-        let map = new LinkedHashMap();
-        Maps._fillMapWithIterables(map, keys, values);
-        return map;
+      removeAll(elements) {
+        for (let element of elements)
+          this.remove(element);
       }
-      LinkedHashMap$_literal(keyValuePairs) {
-        return dart.as(_js_helper.fillLiteralMap(keyValuePairs, new _LinkedHashMap()), LinkedHashMap$(K, V));
+      retainAll(elements) {
+        let toRemove = this.toSet();
+        for (let o of elements) {
+          toRemove.remove(o);
+        }
+        this.removeAll(toRemove);
       }
-      LinkedHashMap$_empty() {
-        return new _LinkedHashMap();
+      removeWhere(test) {
+        let toRemove = new List.from([]);
+        for (let element of this) {
+          if (test(element))
+            toRemove.add(element);
+        }
+        this.removeAll(dart.as(toRemove, core.Iterable$(core.Object)));
       }
-    }
-    dart.defineNamedConstructor(LinkedHashMap, 'identity');
-    dart.defineNamedConstructor(LinkedHashMap, 'from');
-    dart.defineNamedConstructor(LinkedHashMap, 'fromIterable');
-    dart.defineNamedConstructor(LinkedHashMap, 'fromIterables');
-    dart.defineNamedConstructor(LinkedHashMap, '_literal');
-    dart.defineNamedConstructor(LinkedHashMap, '_empty');
-    return LinkedHashMap;
-  });
-  let LinkedHashMap = LinkedHashMap$(dynamic, dynamic);
-  let LinkedHashSet$ = dart.generic(function(E) {
-    class LinkedHashSet extends dart.Object {
-      LinkedHashSet(opt$) {
-        let equals = opt$.equals === void 0 ? null : opt$.equals;
-        let hashCode = opt$.hashCode === void 0 ? null : opt$.hashCode;
-        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
-        if (isValidKey === null) {
-          if (hashCode === null) {
-            if (equals === null) {
-              return new _LinkedHashSet();
-            }
-            hashCode = _defaultHashCode;
-          } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
-              return new _LinkedIdentityHashSet();
-            }
-            if (equals === null) {
-              equals = _defaultEquals;
-            }
-          }
-        } else {
-          if (hashCode === null) {
-            hashCode = _defaultHashCode;
-          }
-          if (equals === null) {
-            equals = _defaultEquals;
-          }
+      retainWhere(test) {
+        let toRemove = new List.from([]);
+        for (let element of this) {
+          if (!dart.notNull(test(element)))
+            toRemove.add(element);
         }
-        return new _LinkedCustomHashSet(equals, hashCode, isValidKey);
+        this.removeAll(dart.as(toRemove, core.Iterable$(core.Object)));
       }
-      LinkedHashSet$identity() {
-        return new _LinkedIdentityHashSet();
+      containsAll(other) {
+        for (let o of other) {
+          if (!dart.notNull(this.contains(o)))
+            return false;
+        }
+        return true;
       }
-      LinkedHashSet$from(elements) {
-        let result = new LinkedHashSet();
-        for (let element of elements) {
-          result.add(element);
+      union(other) {
+        return ((_) => {
+          _.addAll(other);
+          return _;
+        }).bind(this)(this.toSet());
+      }
+      intersection(other) {
+        let result = this.toSet();
+        for (let element of this) {
+          if (!dart.notNull(other.contains(element)))
+            result.remove(element);
         }
         return result;
       }
-    }
-    dart.defineNamedConstructor(LinkedHashSet, 'identity');
-    dart.defineNamedConstructor(LinkedHashSet, 'from');
-    return LinkedHashSet;
-  });
-  let LinkedHashSet = LinkedHashSet$(dynamic);
-  let _modificationCount = Symbol('_modificationCount');
-  let _insertAfter = Symbol('_insertAfter');
-  let _list = Symbol('_list');
-  let _unlink = Symbol('_unlink');
-  let LinkedList$ = dart.generic(function(E) {
-    class LinkedList extends IterableBase$(E) {
-      LinkedList() {
-        this[_modificationCount] = 0;
-        this[_length] = 0;
-        this[_next] = null;
-        this[_previous] = null;
-        super.IterableBase();
-        this[_next] = this[_previous] = this;
+      difference(other) {
+        let result = this.toSet();
+        for (let element of this) {
+          if (other.contains(element))
+            result.remove(element);
+        }
+        return result;
       }
-      addFirst(entry) {
-        this[_insertAfter](this, entry);
+      toList(opt$) {
+        let growable = opt$.growable === void 0 ? true : opt$.growable;
+        let result = growable ? ((_) => {
+          _.length = this.length;
+          return _;
+        }).bind(this)(new core.List()) : new core.List(this.length);
+        let i = 0;
+        for (let element of this)
+          result.set((($tmp) => i = dart.notNull($tmp) + 1, $tmp)(i), element);
+        return result;
       }
-      add(entry) {
-        this[_insertAfter](this[_previous], entry);
+      map(f) {
+        return new _internal.EfficientLengthMappedIterable(this, f);
       }
-      addAll(entries) {
-        entries.forEach(((entry) => this[_insertAfter](this[_previous], dart.as(entry, E))).bind(this));
+      get single() {
+        if (dart.notNull(this.length) > 1)
+          throw _internal.IterableElementError.tooMany();
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext()))
+          throw _internal.IterableElementError.noElement();
+        let result = dart.as(it.current, E);
+        return result;
       }
-      remove(entry) {
-        if (!dart.equals(entry[_list], this))
-          return false;
-        this[_unlink](entry);
-        return true;
+      toString() {
+        return IterableBase.iterableToFullString(this, '{', '}');
       }
-      get iterator() {
-        return new _LinkedListIterator(this);
+      where(f) {
+        return new _internal.WhereIterable(this, f);
       }
-      get length() {
-        return this[_length];
+      expand(f) {
+        return new _internal.ExpandIterable(this, f);
       }
-      clear() {
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        let next = this[_next];
-        while (!dart.notNull(core.identical(next, this))) {
-          let entry = dart.as(next, E);
-          next = entry[_next];
-          entry[_next] = entry[_previous] = entry[_list] = null;
-        }
-        this[_next] = this[_previous] = this;
-        this[_length] = 0;
+      forEach(f) {
+        for (let element of this)
+          f(element);
       }
-      get first() {
-        if (core.identical(this[_next], this)) {
-          throw new core.StateError('No such element');
+      reduce(combine) {
+        let iterator = this.iterator;
+        if (!dart.notNull(iterator.moveNext())) {
+          throw _internal.IterableElementError.noElement();
         }
-        return dart.as(this[_next], E);
-      }
-      get last() {
-        if (core.identical(this[_previous], this)) {
-          throw new core.StateError('No such element');
+        let value = iterator.current;
+        while (iterator.moveNext()) {
+          value = combine(value, iterator.current);
         }
-        return dart.as(this[_previous], E);
+        return value;
       }
-      get single() {
-        if (core.identical(this[_previous], this)) {
-          throw new core.StateError('No such element');
-        }
-        if (!dart.notNull(core.identical(this[_previous], this[_next]))) {
-          throw new core.StateError('Too many elements');
+      fold(initialValue, combine) {
+        let value = initialValue;
+        for (let element of this)
+          value = combine(value, element);
+        return value;
+      }
+      every(f) {
+        for (let element of this) {
+          if (!dart.notNull(f(element)))
+            return false;
         }
-        return dart.as(this[_next], E);
+        return true;
       }
-      forEach(action) {
-        let modificationCount = this[_modificationCount];
-        let current = this[_next];
-        while (!dart.notNull(core.identical(current, this))) {
-          action(dart.as(current, E));
-          if (modificationCount !== this[_modificationCount]) {
-            throw new core.ConcurrentModificationError(this);
+      join(separator) {
+        if (separator === void 0)
+          separator = "";
+        let iterator = this.iterator;
+        if (!dart.notNull(iterator.moveNext()))
+          return "";
+        let buffer = new core.StringBuffer();
+        if (dart.notNull(separator === null) || dart.notNull(dart.equals(separator, ""))) {
+          do {
+            buffer.write(`${iterator.current}`);
+          } while (iterator.moveNext());
+        } else {
+          buffer.write(`${iterator.current}`);
+          while (iterator.moveNext()) {
+            buffer.write(separator);
+            buffer.write(`${iterator.current}`);
           }
-          current = current[_next];
         }
+        return buffer.toString();
       }
-      get isEmpty() {
-        return this[_length] === 0;
-      }
-      [_insertAfter](entry, newEntry) {
-        if (newEntry.list !== null) {
-          throw new core.StateError('LinkedListEntry is already in a LinkedList');
+      any(test) {
+        for (let element of this) {
+          if (test(element))
+            return true;
         }
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        newEntry[_list] = this;
-        let predecessor = entry;
-        let successor = entry[_next];
-        successor[_previous] = newEntry;
-        newEntry[_previous] = predecessor;
-        newEntry[_next] = successor;
-        predecessor[_next] = newEntry;
-        this[_length] = dart.notNull(this[_length]) + 1;
+        return false;
       }
-      [_unlink](entry) {
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        entry[_next][_previous] = entry[_previous];
-        entry[_previous][_next] = entry[_next];
-        this[_length] = dart.notNull(this[_length]) - 1;
-        entry[_list] = entry[_next] = entry[_previous] = null;
+      take(n) {
+        return new _internal.TakeIterable(this, n);
       }
-    }
-    return LinkedList;
-  });
-  let LinkedList = LinkedList$(dynamic);
-  let _LinkedListIterator$ = dart.generic(function(E) {
-    class _LinkedListIterator extends dart.Object {
-      _LinkedListIterator(list) {
-        this[_list] = list;
-        this[_modificationCount] = list[_modificationCount];
-        this[_next] = list[_next];
-        this[_current] = null;
+      takeWhile(test) {
+        return new _internal.TakeWhileIterable(this, test);
       }
-      get current() {
-        return this[_current];
+      skip(n) {
+        return new _internal.SkipIterable(this, n);
       }
-      moveNext() {
-        if (core.identical(this[_next], this[_list])) {
-          this[_current] = null;
-          return false;
-        }
-        if (this[_modificationCount] !== this[_list][_modificationCount]) {
-          throw new core.ConcurrentModificationError(this);
+      skipWhile(test) {
+        return new _internal.SkipWhileIterable(this, test);
+      }
+      get first() {
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext())) {
+          throw _internal.IterableElementError.noElement();
         }
-        this[_current] = dart.as(this[_next], E);
-        this[_next] = this[_next][_next];
-        return true;
-      }
-    }
-    return _LinkedListIterator;
-  });
-  let _LinkedListIterator = _LinkedListIterator$(dynamic);
-  class _LinkedListLink extends dart.Object {
-    _LinkedListLink() {
-      this[_next] = null;
-      this[_previous] = null;
-    }
-  }
-  let LinkedListEntry$ = dart.generic(function(E) {
-    class LinkedListEntry extends dart.Object {
-      LinkedListEntry() {
-        this[_list] = null;
-        this[_next] = null;
-        this[_previous] = null;
-      }
-      get list() {
-        return this[_list];
-      }
-      unlink() {
-        this[_list]._unlink(this);
-      }
-      get next() {
-        if (core.identical(this[_next], this[_list]))
-          return null;
-        let result = dart.as(this[_next], E);
-        return result;
-      }
-      get previous() {
-        if (core.identical(this[_previous], this[_list]))
-          return null;
-        return dart.as(this[_previous], E);
-      }
-      insertAfter(entry) {
-        this[_list]._insertAfter(this, entry);
-      }
-      insertBefore(entry) {
-        this[_list]._insertAfter(this[_previous], entry);
-      }
-    }
-    return LinkedListEntry;
-  });
-  let LinkedListEntry = LinkedListEntry$(dynamic);
-  let ListBase$ = dart.generic(function(E) {
-    class ListBase extends dart.mixin(core.Object, ListMixin$(E)) {
-      static listToString(list) {
-        return IterableBase.iterableToFullString(list, '[', ']');
-      }
-    }
-    return ListBase;
-  });
-  let ListBase = ListBase$(dynamic);
-  let _filter = Symbol('_filter');
-  let ListMixin$ = dart.generic(function(E) {
-    class ListMixin extends dart.Object {
-      get iterator() {
-        return new _internal.ListIterator(this);
-      }
-      elementAt(index) {
-        return this.get(index);
-      }
-      forEach(action) {
-        let length = this.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          action(this.get(i));
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
-          }
-        }
-      }
-      get isEmpty() {
-        return this.length === 0;
-      }
-      get isNotEmpty() {
-        return !dart.notNull(this.isEmpty);
-      }
-      get first() {
-        if (this.length === 0)
-          throw _internal.IterableElementError.noElement();
-        return this.get(0);
+        return dart.as(it.current, E);
       }
       get last() {
-        if (this.length === 0)
-          throw _internal.IterableElementError.noElement();
-        return this.get(dart.notNull(this.length) - 1);
-      }
-      get single() {
-        if (this.length === 0)
+        let it = this.iterator;
+        if (!dart.notNull(it.moveNext())) {
           throw _internal.IterableElementError.noElement();
-        if (dart.notNull(this.length) > 1)
-          throw _internal.IterableElementError.tooMany();
-        return this.get(0);
-      }
-      contains(element) {
-        let length = this.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
-          if (dart.equals(this.get(i), element))
-            return true;
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
-          }
-        }
-        return false;
-      }
-      every(test) {
-        let length = this.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (!dart.notNull(test(this.get(i))))
-            return false;
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
-          }
-        }
-        return true;
-      }
-      any(test) {
-        let length = this.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (test(this.get(i)))
-            return true;
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
-          }
         }
-        return false;
+        let result = null;
+        do {
+          result = dart.as(it.current, E);
+        } while (it.moveNext());
+        return result;
       }
       firstWhere(test, opt$) {
         let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        let length = this.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let element = this.get(i);
+        for (let element of this) {
           if (test(element))
             return element;
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
-          }
         }
         if (orElse !== null)
           return orElse();
@@ -2665,2186 +2525,2312 @@ var collection;
       }
       lastWhere(test, opt$) {
         let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        let length = this.length;
-        for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
-          let element = this.get(i);
-          if (test(element))
-            return element;
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
+        let result = null;
+        let foundMatching = false;
+        for (let element of this) {
+          if (test(element)) {
+            result = element;
+            foundMatching = true;
           }
         }
+        if (foundMatching)
+          return result;
         if (orElse !== null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       singleWhere(test) {
-        let length = this.length;
-        let match = null;
-        let matchFound = false;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let element = this.get(i);
+        let result = null;
+        let foundMatching = false;
+        for (let element of this) {
           if (test(element)) {
-            if (matchFound) {
+            if (foundMatching) {
               throw _internal.IterableElementError.tooMany();
             }
-            matchFound = true;
-            match = element;
-          }
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
+            result = element;
+            foundMatching = true;
           }
         }
-        if (matchFound)
-          return match;
+        if (foundMatching)
+          return result;
         throw _internal.IterableElementError.noElement();
       }
-      join(separator) {
-        if (separator === void 0)
-          separator = "";
-        if (this.length === 0)
-          return "";
-        let buffer = new core.StringBuffer();
-        buffer.writeAll(this, separator);
-        return buffer.toString();
-      }
-      where(test) {
-        return new _internal.WhereIterable(this, test);
-      }
-      map(f) {
-        return new _internal.MappedListIterable(this, dart.as(f, dart.throw_("Unimplemented type (dynamic) → dynamic")));
-      }
-      expand(f) {
-        return new _internal.ExpandIterable(this, f);
-      }
-      reduce(combine) {
-        let length = this.length;
-        if (length === 0)
-          throw _internal.IterableElementError.noElement();
-        let value = this.get(0);
-        for (let i = 1; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          value = combine(value, this.get(i));
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
-          }
-        }
-        return value;
-      }
-      fold(initialValue, combine) {
-        let value = initialValue;
-        let length = this.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          value = combine(value, this.get(i));
-          if (length !== this.length) {
-            throw new core.ConcurrentModificationError(this);
-          }
+      elementAt(index) {
+        if (!(typeof index == number))
+          throw new core.ArgumentError.notNull("index");
+        core.RangeError.checkNotNegative(index, "index");
+        let elementIndex = 0;
+        for (let element of this) {
+          if (index === elementIndex)
+            return element;
+          elementIndex = dart.notNull(elementIndex) + 1;
         }
-        return value;
-      }
-      skip(count) {
-        return new _internal.SubListIterable(this, count, null);
+        throw new core.RangeError.index(index, this, "index", null, elementIndex);
       }
-      skipWhile(test) {
-        return new _internal.SkipWhileIterable(this, test);
+    }
+    return SetMixin;
+  });
+  let SetMixin = SetMixin$(dart.dynamic);
+  let SetBase$ = dart.generic(function(E) {
+    class SetBase extends SetMixin$(E) {
+      static setToString(set) {
+        return IterableBase.iterableToFullString(set, '{', '}');
       }
-      take(count) {
-        return new _internal.SubListIterable(this, 0, count);
+    }
+    return SetBase;
+  });
+  let SetBase = SetBase$(dart.dynamic);
+  let _SplayTreeNode$ = dart.generic(function(K) {
+    class _SplayTreeNode extends core.Object {
+      _SplayTreeNode(key) {
+        this.key = key;
+        this.left = null;
+        this.right = null;
       }
-      takeWhile(test) {
-        return new _internal.TakeWhileIterable(this, test);
+    }
+    return _SplayTreeNode;
+  });
+  let _SplayTreeNode = _SplayTreeNode$(dart.dynamic);
+  let _SplayTreeMapNode$ = dart.generic(function(K, V) {
+    class _SplayTreeMapNode extends _SplayTreeNode$(K) {
+      _SplayTreeMapNode(key, value) {
+        this.value = value;
+        super._SplayTreeNode(key);
       }
-      toList(opt$) {
-        let growable = opt$.growable === void 0 ? true : opt$.growable;
-        let result = null;
-        if (growable) {
-          result = ((_) => {
-            _.length = this.length;
-            return _;
-          }).bind(this)(new core.List());
-        } else {
-          result = new core.List(this.length);
-        }
-        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
-          result.set(i, this.get(i));
+    }
+    return _SplayTreeMapNode;
+  });
+  let _SplayTreeMapNode = _SplayTreeMapNode$(dart.dynamic, dart.dynamic);
+  let _dummy = Symbol('_dummy');
+  let _root = Symbol('_root');
+  let _count = Symbol('_count');
+  let _splayCount = Symbol('_splayCount');
+  let _splay = Symbol('_splay');
+  let _compare = Symbol('_compare');
+  let _splayMin = Symbol('_splayMin');
+  let _splayMax = Symbol('_splayMax');
+  let _addNewRoot = Symbol('_addNewRoot');
+  let _first = Symbol('_first');
+  let _last = Symbol('_last');
+  let _clear = Symbol('_clear');
+  let _SplayTree$ = dart.generic(function(K) {
+    class _SplayTree extends core.Object {
+      _SplayTree() {
+        this[_dummy] = new _SplayTreeNode(null);
+        this[_root] = null;
+        this[_count] = 0;
+        this[_modificationCount] = 0;
+        this[_splayCount] = 0;
+      }
+      [_splay](key) {
+        if (this[_root] === null)
+          return -1;
+        let left = this[_dummy];
+        let right = this[_dummy];
+        let current = this[_root];
+        let comp = null;
+        while (true) {
+          comp = this[_compare](current.key, key);
+          if (dart.notNull(comp) > 0) {
+            if (current.left === null)
+              break;
+            comp = this[_compare](current.left.key, key);
+            if (dart.notNull(comp) > 0) {
+              let tmp = current.left;
+              current.left = tmp.right;
+              tmp.right = current;
+              current = tmp;
+              if (current.left === null)
+                break;
+            }
+            right.left = current;
+            right = current;
+            current = current.left;
+          } else if (dart.notNull(comp) < 0) {
+            if (current.right === null)
+              break;
+            comp = this[_compare](current.right.key, key);
+            if (dart.notNull(comp) < 0) {
+              let tmp = current.right;
+              current.right = tmp.left;
+              tmp.left = current;
+              current = tmp;
+              if (current.right === null)
+                break;
+            }
+            left.right = current;
+            left = current;
+            current = current.right;
+          } else {
+            break;
+          }
         }
-        return result;
+        left.right = current.left;
+        right.left = current.right;
+        current.left = this[_dummy].right;
+        current.right = this[_dummy].left;
+        this[_root] = current;
+        this[_dummy].right = null;
+        this[_dummy].left = null;
+        this[_splayCount] = dart.notNull(this[_splayCount]) + 1;
+        return comp;
       }
-      toSet() {
-        let result = new core.Set();
-        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
-          result.add(this.get(i));
+      [_splayMin](node) {
+        let current = node;
+        while (current.left !== null) {
+          let left = current.left;
+          current.left = left.right;
+          left.right = current;
+          current = left;
         }
-        return result;
+        return dart.as(current, _SplayTreeNode$(K));
       }
-      add(element) {
-        this.set((($tmp) => this.length = dart.notNull($tmp) + 1, $tmp).bind(this)(this.length), element);
+      [_splayMax](node) {
+        let current = node;
+        while (current.right !== null) {
+          let right = current.right;
+          current.right = right.left;
+          right.left = current;
+          current = right;
+        }
+        return dart.as(current, _SplayTreeNode$(K));
       }
-      addAll(iterable) {
-        for (let element of iterable) {
-          this.set((($tmp) => this.length = dart.notNull($tmp) + 1, $tmp).bind(this)(this.length), element);
+      [_remove](key) {
+        if (this[_root] === null)
+          return null;
+        let comp = this[_splay](key);
+        if (comp !== 0)
+          return null;
+        let result = this[_root];
+        this[_count] = dart.notNull(this[_count]) - 1;
+        if (this[_root].left === null) {
+          this[_root] = this[_root].right;
+        } else {
+          let right = this[_root].right;
+          this[_root] = this[_splayMax](this[_root].left);
+          this[_root].right = right;
         }
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        return result;
       }
-      remove(element) {
-        for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
-          if (dart.equals(this.get(i), element)) {
-            this.setRange(i, dart.notNull(this.length) - 1, this, dart.notNull(i) + 1);
-            this.length = 1;
-            return true;
-          }
+      [_addNewRoot](node, comp) {
+        this[_count] = dart.notNull(this[_count]) + 1;
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        if (this[_root] === null) {
+          this[_root] = node;
+          return;
         }
-        return false;
+        if (dart.notNull(comp) < 0) {
+          node.left = this[_root];
+          node.right = this[_root].right;
+          this[_root].right = null;
+        } else {
+          node.right = this[_root];
+          node.left = this[_root].left;
+          this[_root].left = null;
+        }
+        this[_root] = node;
       }
-      removeWhere(test) {
-        _filter(this, dart.as(test, dart.throw_("Unimplemented type (dynamic) → bool")), false);
+      get [_first]() {
+        if (this[_root] === null)
+          return null;
+        this[_root] = this[_splayMin](this[_root]);
+        return this[_root];
       }
-      retainWhere(test) {
-        _filter(this, dart.as(test, dart.throw_("Unimplemented type (dynamic) → bool")), true);
+      get [_last]() {
+        if (this[_root] === null)
+          return null;
+        this[_root] = this[_splayMax](this[_root]);
+        return this[_root];
       }
-      static [_filter](source, test, retainMatching) {
-        let retained = new List.from([]);
-        let length = source.length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          let element = source.get(i);
-          if (test(element) === retainMatching) {
-            retained.add(element);
-          }
-          if (length !== source.length) {
-            throw new core.ConcurrentModificationError(source);
-          }
-        }
-        if (retained.length !== source.length) {
-          source.setRange(0, retained.length, retained);
-          source.length = retained.length;
-        }
+      [_clear]() {
+        this[_root] = null;
+        this[_count] = 0;
+        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
       }
-      clear() {
-        this.length = 0;
+    }
+    return _SplayTree;
+  });
+  let _SplayTree = _SplayTree$(dart.dynamic);
+  let _TypeTest$ = dart.generic(function(T) {
+    class _TypeTest extends core.Object {
+      test(v) {
+        return dart.is(v, T);
       }
-      removeLast() {
-        if (this.length === 0) {
-          throw _internal.IterableElementError.noElement();
-        }
-        let result = this.get(dart.notNull(this.length) - 1);
-        this.length = dart.notNull(this.length) - 1;
-        return result;
+    }
+    return _TypeTest;
+  });
+  let _TypeTest = _TypeTest$(dart.dynamic);
+  let _comparator = Symbol('_comparator');
+  let _validKey = Symbol('_validKey');
+  let SplayTreeMap$ = dart.generic(function(K, V) {
+    class SplayTreeMap extends _SplayTree$(K) {
+      SplayTreeMap(compare, isValidKey) {
+        if (compare === void 0)
+          compare = null;
+        if (isValidKey === void 0)
+          isValidKey = null;
+        this[_comparator] = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
+        this[_validKey] = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, K), _Predicate);
+        super._SplayTree();
       }
-      sort(compare) {
+      SplayTreeMap$from(other, compare, isValidKey) {
         if (compare === void 0)
           compare = null;
-        if (compare === null) {
-          let defaultCompare = core.Comparable.compare;
-          compare = defaultCompare;
-        }
-        _internal.Sort.sort(this, dart.as(compare, dart.throw_("Unimplemented type (dynamic, dynamic) → int")));
+        if (isValidKey === void 0)
+          isValidKey = null;
+        let result = new SplayTreeMap();
+        other.forEach((k, v) => {
+          result.set(k, dart.as(v, V));
+        });
+        return result;
       }
-      shuffle(random) {
-        if (random === void 0)
-          random = null;
-        if (random === null)
-          random = new math.Random();
-        let length = this.length;
-        while (dart.notNull(length) > 1) {
-          let pos = random.nextInt(length);
-          length = 1;
-          let tmp = this.get(length);
-          this.set(length, this.get(pos));
-          this.set(pos, tmp);
-        }
+      SplayTreeMap$fromIterable(iterable, opt$) {
+        let key = opt$.key === void 0 ? null : opt$.key;
+        let value = opt$.value === void 0 ? null : opt$.value;
+        let compare = opt$.compare === void 0 ? null : opt$.compare;
+        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
+        let map = new SplayTreeMap(compare, isValidKey);
+        Maps._fillMapWithMappedIterable(map, iterable, key, value);
+        return map;
       }
-      asMap() {
-        return new _internal.ListMapView(this);
+      SplayTreeMap$fromIterables(keys, values, compare, isValidKey) {
+        if (compare === void 0)
+          compare = null;
+        if (isValidKey === void 0)
+          isValidKey = null;
+        let map = new SplayTreeMap(compare, isValidKey);
+        Maps._fillMapWithIterables(map, keys, values);
+        return map;
       }
-      sublist(start, end) {
-        if (end === void 0)
-          end = null;
-        let listLength = this.length;
-        if (end === null)
-          end = listLength;
-        core.RangeError.checkValidRange(start, end, listLength);
-        let length = dart.notNull(end) - dart.notNull(start);
-        let result = new core.List();
-        result.length = length;
-        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          result.set(i, this.get(dart.notNull(start) + dart.notNull(i)));
-        }
-        return result;
-      }
-      getRange(start, end) {
-        core.RangeError.checkValidRange(start, end, this.length);
-        return new _internal.SubListIterable(this, start, end);
-      }
-      removeRange(start, end) {
-        core.RangeError.checkValidRange(start, end, this.length);
-        let length = dart.notNull(end) - dart.notNull(start);
-        this.setRange(start, dart.notNull(this.length) - dart.notNull(length), this, end);
-        this.length = length;
+      [_compare](key1, key2) {
+        return this[_comparator](key1, key2);
       }
-      fillRange(start, end, fill) {
-        if (fill === void 0)
-          fill = null;
-        core.RangeError.checkValidRange(start, end, this.length);
-        for (let i = start; dart.notNull(i) < dart.notNull(end); i = dart.notNull(i) + 1) {
-          this.set(i, fill);
-        }
+      SplayTreeMap$_internal() {
+        this[_comparator] = null;
+        this[_validKey] = null;
+        super._SplayTree();
       }
-      setRange(start, end, iterable, skipCount) {
-        if (skipCount === void 0)
-          skipCount = 0;
-        core.RangeError.checkValidRange(start, end, this.length);
-        let length = dart.notNull(end) - dart.notNull(start);
-        if (length === 0)
-          return;
-        core.RangeError.checkNotNegative(skipCount, "skipCount");
-        let otherList = null;
-        let otherStart = null;
-        if (dart.is(iterable, core.List)) {
-          otherList = dart.as(iterable, core.List);
-          otherStart = skipCount;
-        } else {
-          otherList = iterable.skip(skipCount).toList({growable: false});
-          otherStart = 0;
-        }
-        if (dart.notNull(otherStart) + dart.notNull(length) > dart.notNull(otherList.length)) {
-          throw _internal.IterableElementError.tooFew();
-        }
-        if (dart.notNull(otherStart) < dart.notNull(start)) {
-          for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
-            this.set(dart.notNull(start) + dart.notNull(i), dart.as(otherList.get(dart.notNull(otherStart) + dart.notNull(i)), E));
-          }
-        } else {
-          for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-            this.set(dart.notNull(start) + dart.notNull(i), dart.as(otherList.get(dart.notNull(otherStart) + dart.notNull(i)), E));
+      get(key) {
+        if (key === null)
+          throw new core.ArgumentError(key);
+        if (!dart.notNull(this[_validKey](key)))
+          return null;
+        if (this[_root] !== null) {
+          let comp = this[_splay](dart.as(key, K));
+          if (comp === 0) {
+            let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
+            return dart.as(mapRoot.value, V);
           }
         }
+        return null;
       }
-      replaceRange(start, end, newContents) {
-        core.RangeError.checkValidRange(start, end, this.length);
-        if (!dart.is(newContents, _internal.EfficientLength)) {
-          newContents = newContents.toList();
-        }
-        let removeLength = dart.notNull(end) - dart.notNull(start);
-        let insertLength = newContents.length;
-        if (dart.notNull(removeLength) >= dart.notNull(insertLength)) {
-          let delta = dart.notNull(removeLength) - dart.notNull(insertLength);
-          let insertEnd = dart.notNull(start) + dart.notNull(insertLength);
-          let newLength = dart.notNull(this.length) - dart.notNull(delta);
-          this.setRange(start, insertEnd, newContents);
-          if (delta !== 0) {
-            this.setRange(insertEnd, newLength, this, end);
-            this.length = newLength;
-          }
-        } else {
-          let delta = dart.notNull(insertLength) - dart.notNull(removeLength);
-          let newLength = dart.notNull(this.length) + dart.notNull(delta);
-          let insertEnd = dart.notNull(start) + dart.notNull(insertLength);
-          this.length = newLength;
-          this.setRange(insertEnd, newLength, this, end);
-          this.setRange(start, insertEnd, newContents);
+      remove(key) {
+        if (!dart.notNull(this[_validKey](key)))
+          return null;
+        let mapRoot = dart.as(this[_remove](dart.as(key, K)), _SplayTreeMapNode);
+        if (mapRoot !== null)
+          return dart.as(mapRoot.value, V);
+        return null;
+      }
+      set(key, value) {
+        if (key === null)
+          throw new core.ArgumentError(key);
+        let comp = this[_splay](key);
+        if (comp === 0) {
+          let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
+          mapRoot.value = value;
+          return;
         }
+        this[_addNewRoot](dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
       }
-      indexOf(element, startIndex) {
-        if (startIndex === void 0)
-          startIndex = 0;
-        if (dart.notNull(startIndex) >= dart.notNull(this.length)) {
-          return -1;
+      putIfAbsent(key, ifAbsent) {
+        if (key === null)
+          throw new core.ArgumentError(key);
+        let comp = this[_splay](key);
+        if (comp === 0) {
+          let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
+          return dart.as(mapRoot.value, V);
         }
-        if (dart.notNull(startIndex) < 0) {
-          startIndex = 0;
+        let modificationCount = this[_modificationCount];
+        let splayCount = this[_splayCount];
+        let value = ifAbsent();
+        if (modificationCount !== this[_modificationCount]) {
+          throw new core.ConcurrentModificationError(this);
         }
-        for (let i = startIndex; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
-          if (dart.equals(this.get(i), element)) {
-            return i;
-          }
+        if (splayCount !== this[_splayCount]) {
+          comp = this[_splay](key);
+          dart.assert(comp !== 0);
         }
-        return -1;
+        this[_addNewRoot](dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
+        return value;
       }
-      lastIndexOf(element, startIndex) {
-        if (startIndex === void 0)
-          startIndex = null;
-        if (startIndex === null) {
-          startIndex = dart.notNull(this.length) - 1;
-        } else {
-          if (dart.notNull(startIndex) < 0) {
-            return -1;
-          }
-          if (dart.notNull(startIndex) >= dart.notNull(this.length)) {
-            startIndex = dart.notNull(this.length) - 1;
-          }
-        }
-        for (let i = startIndex; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
-          if (dart.equals(this.get(i), element)) {
-            return i;
-          }
-        }
-        return -1;
+      addAll(other) {
+        other.forEach(((key, value) => {
+          this.set(key, value);
+        }).bind(this));
       }
-      insert(index, element) {
-        core.RangeError.checkValueInInterval(index, 0, this.length, "index");
-        if (index === this.length) {
-          this.add(element);
-          return;
-        }
-        if (!(typeof index == number))
-          throw new core.ArgumentError(index);
-        this.length = dart.notNull(this.length) + 1;
-        this.setRange(dart.notNull(index) + 1, this.length, this, index);
-        this.set(index, element);
+      get isEmpty() {
+        return this[_root] === null;
       }
-      removeAt(index) {
-        let result = this.get(index);
-        this.setRange(index, dart.notNull(this.length) - 1, this, dart.notNull(index) + 1);
-        this.length = dart.notNull(this.length) - 1;
-        return result;
+      get isNotEmpty() {
+        return !dart.notNull(this.isEmpty);
       }
-      insertAll(index, iterable) {
-        core.RangeError.checkValueInInterval(index, 0, this.length, "index");
-        if (dart.is(iterable, _internal.EfficientLength)) {
-          iterable = iterable.toList();
+      forEach(f) {
+        let nodes = new _SplayTreeNodeIterator(this);
+        while (nodes.moveNext()) {
+          let node = dart.as(nodes.current, _SplayTreeMapNode$(K, V));
+          f(node.key, node.value);
         }
-        let insertionLength = iterable.length;
-        this.length = insertionLength;
-        this.setRange(dart.notNull(index) + dart.notNull(insertionLength), this.length, this, index);
-        this.setAll(index, iterable);
       }
-      setAll(index, iterable) {
-        if (dart.is(iterable, core.List)) {
-          this.setRange(index, dart.notNull(index) + dart.notNull(iterable.length), iterable);
-        } else {
-          for (let element of iterable) {
-            this.set((($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index), element);
+      get length() {
+        return this[_count];
+      }
+      clear() {
+        this[_clear]();
+      }
+      containsKey(key) {
+        return dart.notNull(this[_validKey](key)) && this[_splay](dart.as(key, K)) === 0;
+      }
+      containsValue(value) {
+        let found = false;
+        let initialSplayCount = this[_splayCount];
+        // Function visit: (_SplayTreeMapNode<dynamic, dynamic>) → bool
+        function visit(node) {
+          while (node !== null) {
+            if (dart.equals(node.value, value))
+              return true;
+            if (initialSplayCount !== this[_splayCount]) {
+              throw new core.ConcurrentModificationError(this);
+            }
+            if (dart.notNull(node.right !== null) && dart.notNull(visit(dart.as(node.right, _SplayTreeMapNode))))
+              return true;
+            node = dart.as(node.left, _SplayTreeMapNode);
           }
+          return false;
         }
+        return visit(dart.as(this[_root], _SplayTreeMapNode));
       }
-      get reversed() {
-        return new _internal.ReversedListIterable(this);
+      get keys() {
+        return new _SplayTreeKeyIterable(this);
+      }
+      get values() {
+        return new _SplayTreeValueIterable(this);
       }
       toString() {
-        return IterableBase.iterableToFullString(this, '[', ']');
+        return Maps.mapToString(this);
       }
-    }
-    return ListMixin;
-  });
-  let ListMixin = ListMixin$(dynamic);
-  let MapBase$ = dart.generic(function(K, V) {
-    class MapBase extends dart.mixin(MapMixin$(K, V)) {
-    }
-    return MapBase;
-  });
-  let MapBase = MapBase$(dynamic, dynamic);
-  let MapMixin$ = dart.generic(function(K, V) {
-    class MapMixin extends dart.Object {
-      forEach(action) {
-        for (let key of this.keys) {
-          action(key, this.get(key));
-        }
+      firstKey() {
+        if (this[_root] === null)
+          return null;
+        return dart.as(this[_first].key, K);
       }
-      addAll(other) {
-        for (let key of other.keys) {
-          this.set(key, other.get(key));
-        }
+      lastKey() {
+        if (this[_root] === null)
+          return null;
+        return dart.as(this[_last].key, K);
       }
-      containsValue(value) {
-        for (let key of this.keys) {
-          if (dart.equals(this.get(key), value))
-            return true;
+      lastKeyBefore(key) {
+        if (key === null)
+          throw new core.ArgumentError(key);
+        if (this[_root] === null)
+          return null;
+        let comp = this[_splay](key);
+        if (dart.notNull(comp) < 0)
+          return this[_root].key;
+        let node = this[_root].left;
+        if (node === null)
+          return null;
+        while (node.right !== null) {
+          node = node.right;
         }
-        return false;
+        return node.key;
       }
-      putIfAbsent(key, ifAbsent) {
-        if (this.keys.contains(key)) {
-          return this.get(key);
+      firstKeyAfter(key) {
+        if (key === null)
+          throw new core.ArgumentError(key);
+        if (this[_root] === null)
+          return null;
+        let comp = this[_splay](key);
+        if (dart.notNull(comp) > 0)
+          return this[_root].key;
+        let node = this[_root].right;
+        if (node === null)
+          return null;
+        while (node.left !== null) {
+          node = node.left;
         }
-        return this.set(key, ifAbsent());
+        return node.key;
       }
-      containsKey(key) {
-        return this.keys.contains(key);
+    }
+    dart.defineNamedConstructor(SplayTreeMap, 'from');
+    dart.defineNamedConstructor(SplayTreeMap, 'fromIterable');
+    dart.defineNamedConstructor(SplayTreeMap, 'fromIterables');
+    dart.defineNamedConstructor(SplayTreeMap, '_internal');
+    return SplayTreeMap;
+  });
+  let SplayTreeMap = SplayTreeMap$(dart.dynamic, dart.dynamic);
+  let _workList = Symbol('_workList');
+  let _tree = Symbol('_tree');
+  let _currentNode = Symbol('_currentNode');
+  let _findLeftMostDescendent = Symbol('_findLeftMostDescendent');
+  let _getValue = Symbol('_getValue');
+  let _rebuildWorkList = Symbol('_rebuildWorkList');
+  let _SplayTreeIterator$ = dart.generic(function(T) {
+    class _SplayTreeIterator extends core.Object {
+      _SplayTreeIterator(tree) {
+        this[_workList] = new List.from([]);
+        this[_tree] = tree;
+        this[_modificationCount] = tree[_modificationCount];
+        this[_splayCount] = tree[_splayCount];
+        this[_currentNode] = null;
+        this[_findLeftMostDescendent](tree[_root]);
       }
-      get length() {
-        return this.keys.length;
+      _SplayTreeIterator$startAt(tree, startKey) {
+        this[_workList] = new List.from([]);
+        this[_tree] = tree;
+        this[_modificationCount] = tree[_modificationCount];
+        this[_splayCount] = null;
+        this[_currentNode] = null;
+        if (tree[_root] === null)
+          return;
+        let compare = tree._splay(startKey);
+        this[_splayCount] = tree[_splayCount];
+        if (dart.notNull(compare) < 0) {
+          this[_findLeftMostDescendent](tree[_root].right);
+        } else {
+          this[_workList].add(tree[_root]);
+        }
       }
-      get isEmpty() {
-        return this.keys.isEmpty;
+      get current() {
+        if (this[_currentNode] === null)
+          return null;
+        return this[_getValue](this[_currentNode]);
       }
-      get isNotEmpty() {
-        return this.keys.isNotEmpty;
+      [_findLeftMostDescendent](node) {
+        while (node !== null) {
+          this[_workList].add(node);
+          node = node.left;
+        }
       }
-      get values() {
-        return new _MapBaseValueIterable(this);
+      [_rebuildWorkList](currentNode) {
+        dart.assert(!dart.notNull(this[_workList].isEmpty));
+        this[_workList].clear();
+        if (currentNode === null) {
+          this[_findLeftMostDescendent](this[_tree][_root]);
+        } else {
+          this[_tree]._splay(currentNode.key);
+          this[_findLeftMostDescendent](this[_tree][_root].right);
+          dart.assert(!dart.notNull(this[_workList].isEmpty));
+        }
       }
-      toString() {
-        return Maps.mapToString(this);
+      moveNext() {
+        if (this[_modificationCount] !== this[_tree][_modificationCount]) {
+          throw new core.ConcurrentModificationError(this[_tree]);
+        }
+        if (this[_workList].isEmpty) {
+          this[_currentNode] = null;
+          return false;
+        }
+        if (this[_tree][_splayCount] !== this[_splayCount] && dart.notNull(this[_currentNode] !== null)) {
+          this[_rebuildWorkList](this[_currentNode]);
+        }
+        this[_currentNode] = this[_workList].removeLast();
+        this[_findLeftMostDescendent](this[_currentNode].right);
+        return true;
       }
     }
-    return MapMixin;
-  });
-  let MapMixin = MapMixin$(dynamic, dynamic);
-  let UnmodifiableMapBase$ = dart.generic(function(K, V) {
-    class UnmodifiableMapBase extends dart.mixin(_UnmodifiableMapMixin$(K, V)) {
-    }
-    return UnmodifiableMapBase;
+    dart.defineNamedConstructor(_SplayTreeIterator, 'startAt');
+    return _SplayTreeIterator;
   });
-  let UnmodifiableMapBase = UnmodifiableMapBase$(dynamic, dynamic);
-  let _MapBaseValueIterable$ = dart.generic(function(V) {
-    class _MapBaseValueIterable extends IterableBase$(V) {
-      _MapBaseValueIterable($_map) {
-        this[_map] = $_map;
+  let _SplayTreeIterator = _SplayTreeIterator$(dart.dynamic);
+  let _SplayTreeKeyIterable$ = dart.generic(function(K) {
+    class _SplayTreeKeyIterable extends IterableBase$(K) {
+      _SplayTreeKeyIterable($_tree) {
+        this[_tree] = $_tree;
         super.IterableBase();
       }
       get length() {
-        return this[_map].length;
+        return this[_tree][_count];
       }
       get isEmpty() {
-        return this[_map].isEmpty;
+        return this[_tree][_count] === 0;
       }
-      get isNotEmpty() {
-        return this[_map].isNotEmpty;
+      get iterator() {
+        return new _SplayTreeKeyIterator(this[_tree]);
       }
-      get first() {
-        return dart.as(this[_map].get(this[_map].keys.first), V);
+      toSet() {
+        let setOrMap = this[_tree];
+        let set = new SplayTreeSet(dart.as(setOrMap[_comparator], dart.throw_("Unimplemented type (K, K) → int")), dart.as(setOrMap[_validKey], dart.throw_("Unimplemented type (dynamic) → bool")));
+        set[_count] = this[_tree][_count];
+        set[_root] = set._copyNode(this[_tree][_root]);
+        return set;
       }
-      get single() {
-        return dart.as(this[_map].get(this[_map].keys.single), V);
+    }
+    return _SplayTreeKeyIterable;
+  });
+  let _SplayTreeKeyIterable = _SplayTreeKeyIterable$(dart.dynamic);
+  let _SplayTreeValueIterable$ = dart.generic(function(K, V) {
+    class _SplayTreeValueIterable extends IterableBase$(V) {
+      _SplayTreeValueIterable($_map) {
+        this[_map] = $_map;
+        super.IterableBase();
       }
-      get last() {
-        return dart.as(this[_map].get(this[_map].keys.last), V);
+      get length() {
+        return this[_map][_count];
+      }
+      get isEmpty() {
+        return this[_map][_count] === 0;
       }
       get iterator() {
-        return new _MapBaseValueIterator(this[_map]);
+        return new _SplayTreeValueIterator(this[_map]);
       }
     }
-    return _MapBaseValueIterable;
+    return _SplayTreeValueIterable;
   });
-  let _MapBaseValueIterable = _MapBaseValueIterable$(dynamic);
-  let _MapBaseValueIterator$ = dart.generic(function(V) {
-    class _MapBaseValueIterator extends dart.Object {
-      _MapBaseValueIterator(map) {
-        this[_map] = map;
-        this[_keys] = map.keys.iterator;
-        this[_current] = null;
-      }
-      moveNext() {
-        if (this[_keys].moveNext()) {
-          this[_current] = dart.as(this[_map].get(this[_keys].current), V);
-          return true;
-        }
-        this[_current] = null;
-        return false;
+  let _SplayTreeValueIterable = _SplayTreeValueIterable$(dart.dynamic, dart.dynamic);
+  let _SplayTreeKeyIterator$ = dart.generic(function(K) {
+    class _SplayTreeKeyIterator extends _SplayTreeIterator$(K) {
+      _SplayTreeKeyIterator(map) {
+        super._SplayTreeIterator(map);
       }
-      get current() {
-        return this[_current];
+      [_getValue](node) {
+        return dart.as(node.key, K);
       }
     }
-    return _MapBaseValueIterator;
+    return _SplayTreeKeyIterator;
   });
-  let _MapBaseValueIterator = _MapBaseValueIterator$(dynamic);
-  let _UnmodifiableMapMixin$ = dart.generic(function(K, V) {
-    class _UnmodifiableMapMixin extends dart.Object {
-      set(key, value) {
-        throw new core.UnsupportedError("Cannot modify unmodifiable map");
+  let _SplayTreeKeyIterator = _SplayTreeKeyIterator$(dart.dynamic);
+  let _SplayTreeValueIterator$ = dart.generic(function(K, V) {
+    class _SplayTreeValueIterator extends _SplayTreeIterator$(V) {
+      _SplayTreeValueIterator(map) {
+        super._SplayTreeIterator(map);
       }
-      addAll(other) {
-        throw new core.UnsupportedError("Cannot modify unmodifiable map");
+      [_getValue](node) {
+        return dart.as(node.value, V);
       }
-      clear() {
-        throw new core.UnsupportedError("Cannot modify unmodifiable map");
+    }
+    return _SplayTreeValueIterator;
+  });
+  let _SplayTreeValueIterator = _SplayTreeValueIterator$(dart.dynamic, dart.dynamic);
+  let _SplayTreeNodeIterator$ = dart.generic(function(K) {
+    class _SplayTreeNodeIterator extends _SplayTreeIterator$(_SplayTreeNode$(K)) {
+      _SplayTreeNodeIterator(tree) {
+        super._SplayTreeIterator(tree);
       }
-      remove(key) {
-        throw new core.UnsupportedError("Cannot modify unmodifiable map");
+      _SplayTreeNodeIterator$startAt(tree, startKey) {
+        super._SplayTreeIterator$startAt(tree, startKey);
       }
-      putIfAbsent(key, ifAbsent) {
-        throw new core.UnsupportedError("Cannot modify unmodifiable map");
+      [_getValue](node) {
+        return dart.as(node, _SplayTreeNode$(K));
       }
     }
-    return _UnmodifiableMapMixin;
+    dart.defineNamedConstructor(_SplayTreeNodeIterator, 'startAt');
+    return _SplayTreeNodeIterator;
   });
-  let _UnmodifiableMapMixin = _UnmodifiableMapMixin$(dynamic, dynamic);
-  let MapView$ = dart.generic(function(K, V) {
-    class MapView extends dart.Object {
-      MapView(map) {
-        this[_map] = map;
-      }
-      get(key) {
-        return this[_map].get(key);
-      }
-      set(key, value) {
-        this[_map].set(key, value);
+  let _SplayTreeNodeIterator = _SplayTreeNodeIterator$(dart.dynamic);
+  let _clone = Symbol('_clone');
+  let _copyNode = Symbol('_copyNode');
+  let SplayTreeSet$ = dart.generic(function(E) {
+    class SplayTreeSet extends dart.mixin(_SplayTree$(E), IterableMixin$(E), SetMixin$(E)) {
+      SplayTreeSet(compare, isValidKey) {
+        if (compare === void 0)
+          compare = null;
+        if (isValidKey === void 0)
+          isValidKey = null;
+        this[_comparator] = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
+        this[_validKey] = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, E), _Predicate);
+        super._SplayTree();
       }
-      addAll(other) {
-        this[_map].addAll(other);
-      }
-      clear() {
-        this[_map].clear();
-      }
-      putIfAbsent(key, ifAbsent) {
-        return this[_map].putIfAbsent(key, ifAbsent);
+      SplayTreeSet$from(elements, compare, isValidKey) {
+        if (compare === void 0)
+          compare = null;
+        if (isValidKey === void 0)
+          isValidKey = null;
+        let result = new SplayTreeSet(compare, isValidKey);
+        for (let element of elements) {
+          result.add(element);
+        }
+        return result;
       }
-      containsKey(key) {
-        return this[_map].containsKey(key);
+      [_compare](e1, e2) {
+        return this[_comparator](e1, e2);
       }
-      containsValue(value) {
-        return this[_map].containsValue(value);
+      get iterator() {
+        return new _SplayTreeKeyIterator(this);
       }
-      forEach(action) {
-        this[_map].forEach(action);
+      get length() {
+        return this[_count];
       }
       get isEmpty() {
-        return this[_map].isEmpty;
+        return this[_root] === null;
       }
       get isNotEmpty() {
-        return this[_map].isNotEmpty;
+        return this[_root] !== null;
       }
-      get length() {
-        return this[_map].length;
+      get first() {
+        if (this[_count] === 0)
+          throw _internal.IterableElementError.noElement();
+        return dart.as(this[_first].key, E);
       }
-      get keys() {
-        return this[_map].keys;
+      get last() {
+        if (this[_count] === 0)
+          throw _internal.IterableElementError.noElement();
+        return dart.as(this[_last].key, E);
       }
-      remove(key) {
-        return this[_map].remove(key);
+      get single() {
+        if (this[_count] === 0)
+          throw _internal.IterableElementError.noElement();
+        if (dart.notNull(this[_count]) > 1)
+          throw _internal.IterableElementError.tooMany();
+        return this[_root].key;
       }
-      toString() {
-        return this[_map].toString();
+      contains(object) {
+        return dart.notNull(this[_validKey](object)) && this[_splay](dart.as(object, E)) === 0;
       }
-      get values() {
-        return this[_map].values;
+      add(element) {
+        let compare = this[_splay](element);
+        if (compare === 0)
+          return false;
+        this[_addNewRoot](dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
+        return true;
       }
-    }
-    return MapView;
-  });
-  let MapView = MapView$(dynamic, dynamic);
-  let UnmodifiableMapView$ = dart.generic(function(K, V) {
-    class UnmodifiableMapView extends dart.mixin(_UnmodifiableMapMixin$(K, V)) {
-    }
-    return UnmodifiableMapView;
-  });
-  let UnmodifiableMapView = UnmodifiableMapView$(dynamic, dynamic);
-  let _toStringVisiting = Symbol('_toStringVisiting');
-  let _id = Symbol('_id');
-  let _fillMapWithMappedIterable = Symbol('_fillMapWithMappedIterable');
-  let _fillMapWithIterables = Symbol('_fillMapWithIterables');
-  class Maps extends dart.Object {
-    static containsValue(map, value) {
-      for (let v of map.values) {
-        if (dart.equals(value, v)) {
-          return true;
+      remove(object) {
+        if (!dart.notNull(this[_validKey](object)))
+          return false;
+        return this[_remove](dart.as(object, E)) !== null;
+      }
+      addAll(elements) {
+        for (let element of elements) {
+          let compare = this[_splay](element);
+          if (compare !== 0) {
+            this[_addNewRoot](dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
+          }
         }
       }
-      return false;
-    }
-    static containsKey(map, key) {
-      for (let k of map.keys) {
-        if (dart.equals(key, k)) {
-          return true;
+      removeAll(elements) {
+        for (let element of elements) {
+          if (this[_validKey](element))
+            this[_remove](dart.as(element, E));
         }
       }
-      return false;
-    }
-    static putIfAbsent(map, key, ifAbsent) {
-      if (map.containsKey(key)) {
-        return map.get(key);
+      retainAll(elements) {
+        let retainSet = new SplayTreeSet(this[_comparator], this[_validKey]);
+        let modificationCount = this[_modificationCount];
+        for (let object of elements) {
+          if (modificationCount !== this[_modificationCount]) {
+            throw new core.ConcurrentModificationError(this);
+          }
+          if (dart.notNull(this[_validKey](object)) && this[_splay](dart.as(object, E)) === 0)
+            retainSet.add(this[_root].key);
+        }
+        if (retainSet[_count] !== this[_count]) {
+          this[_root] = retainSet[_root];
+          this[_count] = retainSet[_count];
+          this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+        }
       }
-      let v = ifAbsent();
-      map.set(key, v);
-      return v;
-    }
-    static clear(map) {
-      for (let k of map.keys.toList()) {
-        map.remove(k);
+      lookup(object) {
+        if (!dart.notNull(this[_validKey](object)))
+          return null;
+        let comp = this[_splay](dart.as(object, E));
+        if (comp !== 0)
+          return null;
+        return this[_root].key;
       }
-    }
-    static forEach(map, f) {
-      for (let k of map.keys) {
-        f(k, map.get(k));
+      intersection(other) {
+        let result = new SplayTreeSet(this[_comparator], this[_validKey]);
+        for (let element of this) {
+          if (other.contains(element))
+            result.add(element);
+        }
+        return result;
       }
-    }
-    static getValues(map) {
-      return map.keys.map((key) => map.get(key));
-    }
-    static length(map) {
-      return map.keys.length;
-    }
-    static isEmpty(map) {
-      return map.keys.isEmpty;
-    }
-    static isNotEmpty(map) {
-      return map.keys.isNotEmpty;
-    }
-    static mapToString(m) {
-      if (IterableBase._isToStringVisiting(m)) {
-        return '{...}';
+      difference(other) {
+        let result = new SplayTreeSet(this[_comparator], this[_validKey]);
+        for (let element of this) {
+          if (!dart.notNull(other.contains(element)))
+            result.add(element);
+        }
+        return result;
       }
-      let result = new core.StringBuffer();
-      try {
-        IterableBase[_toStringVisiting].add(m);
-        result.write('{');
-        let first = true;
-        m.forEach(((k, v) => {
-          if (!dart.notNull(first)) {
-            result.write(', ');
-          }
-          first = false;
-          result.write(k);
-          result.write(': ');
-          result.write(v);
-        }).bind(this));
-        result.write('}');
-      } finally {
-        dart.assert(core.identical(IterableBase[_toStringVisiting].last, m));
-        IterableBase[_toStringVisiting].removeLast();
+      union(other) {
+        return ((_) => {
+          _.addAll(other);
+          return _;
+        }).bind(this)(this[_clone]());
       }
-      return result.toString();
-    }
-    static [_id](x) {
-      return x;
-    }
-    static [_fillMapWithMappedIterable](map, iterable, key, value) {
-      if (key === null)
-        key = _id;
-      if (value === null)
-        value = _id;
-      for (let element of iterable) {
-        map.set(key(element), value(element));
+      [_clone]() {
+        let set = new SplayTreeSet(this[_comparator], this[_validKey]);
+        set[_count] = this[_count];
+        set[_root] = this[_copyNode](this[_root]);
+        return set;
       }
-    }
-    static [_fillMapWithIterables](map, keys, values) {
-      let keyIterator = keys.iterator;
-      let valueIterator = values.iterator;
-      let hasNextKey = keyIterator.moveNext();
-      let hasNextValue = valueIterator.moveNext();
-      while (dart.notNull(hasNextKey) && dart.notNull(hasNextValue)) {
-        map.set(keyIterator.current, valueIterator.current);
-        hasNextKey = keyIterator.moveNext();
-        hasNextValue = valueIterator.moveNext();
+      [_copyNode](node) {
+        if (node === null)
+          return null;
+        return ((_) => {
+          _.left = this[_copyNode](node.left);
+          _.right = this[_copyNode](node.right);
+          return _;
+        }).bind(this)(new _SplayTreeNode(node.key));
       }
-      if (dart.notNull(hasNextKey) || dart.notNull(hasNextValue)) {
-        throw new core.ArgumentError("Iterables do not have same length.");
+      clear() {
+        this[_clear]();
       }
-    }
-  }
-  let Queue$ = dart.generic(function(E) {
-    class Queue extends dart.Object {
-      Queue() {
-        return new ListQueue();
+      toSet() {
+        return this[_clone]();
       }
-      Queue$from(elements) {
-        return new ListQueue.from(elements);
+      toString() {
+        return IterableBase.iterableToFullString(this, '{', '}');
       }
     }
-    dart.defineNamedConstructor(Queue, 'from');
-    return Queue;
+    dart.defineNamedConstructor(SplayTreeSet, 'from');
+    return SplayTreeSet;
   });
-  let Queue = Queue$(dynamic);
-  let _link = Symbol('_link');
-  let _asNonSentinelEntry = Symbol('_asNonSentinelEntry');
-  let DoubleLinkedQueueEntry$ = dart.generic(function(E) {
-    class DoubleLinkedQueueEntry extends dart.Object {
-      DoubleLinkedQueueEntry(e) {
-        this[_element] = e;
-        this[_previous] = null;
-        this[_next] = null;
-      }
-      [_link](previous, next) {
-        this[_next] = next;
-        this[_previous] = previous;
-        previous[_next] = this;
-        next[_previous] = this;
-      }
-      append(e) {
-        new DoubleLinkedQueueEntry(e)._link(this, this[_next]);
-      }
-      prepend(e) {
-        new DoubleLinkedQueueEntry(e)._link(this[_previous], this);
-      }
-      remove() {
-        this[_previous][_next] = this[_next];
-        this[_next][_previous] = this[_previous];
-        this[_next] = null;
-        this[_previous] = null;
-        return this[_element];
-      }
-      [_asNonSentinelEntry]() {
-        return this;
-      }
-      previousEntry() {
-        return this[_previous]._asNonSentinelEntry();
-      }
-      nextEntry() {
-        return this[_next]._asNonSentinelEntry();
-      }
-      get element() {
-        return this[_element];
-      }
-      set element(e) {
-        this[_element] = e;
-      }
-    }
-    return DoubleLinkedQueueEntry;
-  });
-  let DoubleLinkedQueueEntry = DoubleLinkedQueueEntry$(dynamic);
-  let _DoubleLinkedQueueEntrySentinel$ = dart.generic(function(E) {
-    class _DoubleLinkedQueueEntrySentinel extends DoubleLinkedQueueEntry$(E) {
-      _DoubleLinkedQueueEntrySentinel() {
-        super.DoubleLinkedQueueEntry(null);
-        this[_link](this, this);
+  let SplayTreeSet = SplayTreeSet$(dart.dynamic);
+  let _strings = Symbol('_strings');
+  let _nums = Symbol('_nums');
+  let _rest = Symbol('_rest');
+  let _containsKey = Symbol('_containsKey');
+  let _getBucket = Symbol('_getBucket');
+  let _findBucketIndex = Symbol('_findBucketIndex');
+  let _computeKeys = Symbol('_computeKeys');
+  let _get = Symbol('_get');
+  let _addHashTableEntry = Symbol('_addHashTableEntry');
+  let _set = Symbol('_set');
+  let _computeHashCode = Symbol('_computeHashCode');
+  let _removeHashTableEntry = Symbol('_removeHashTableEntry');
+  let _isStringKey = Symbol('_isStringKey');
+  let _isNumericKey = Symbol('_isNumericKey');
+  let _hasTableEntry = Symbol('_hasTableEntry');
+  let _getTableEntry = Symbol('_getTableEntry');
+  let _setTableEntry = Symbol('_setTableEntry');
+  let _deleteTableEntry = Symbol('_deleteTableEntry');
+  let _newHashTable = Symbol('_newHashTable');
+  let _HashMap$ = dart.generic(function(K, V) {
+    class _HashMap extends core.Object {
+      _HashMap() {
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_keys] = null;
       }
-      remove() {
-        throw _internal.IterableElementError.noElement();
+      get length() {
+        return this[_length];
       }
-      [_asNonSentinelEntry]() {
-        return null;
+      get isEmpty() {
+        return this[_length] === 0;
       }
-      set element(e) {
-        dart.assert(false);
+      get isNotEmpty() {
+        return !dart.notNull(this.isEmpty);
       }
-      get element() {
-        throw _internal.IterableElementError.noElement();
+      get keys() {
+        return new HashMapKeyIterable(this);
       }
-    }
-    return _DoubleLinkedQueueEntrySentinel;
-  });
-  let _DoubleLinkedQueueEntrySentinel = _DoubleLinkedQueueEntrySentinel$(dynamic);
-  let _sentinel = Symbol('_sentinel');
-  let _elementCount = Symbol('_elementCount');
-  let DoubleLinkedQueue$ = dart.generic(function(E) {
-    class DoubleLinkedQueue extends IterableBase$(E) {
-      DoubleLinkedQueue() {
-        this[_sentinel] = null;
-        this[_elementCount] = 0;
-        super.IterableBase();
-        this[_sentinel] = new _DoubleLinkedQueueEntrySentinel();
+      get values() {
+        return new _internal.MappedIterable(this.keys, ((each) => this.get(each)).bind(this));
       }
-      DoubleLinkedQueue$from(elements) {
-        let list = dart.as(new DoubleLinkedQueue(), Queue$(E));
-        for (let e of elements) {
-          list.addLast(e);
+      containsKey(key) {
+        if (_isStringKey(key)) {
+          let strings = this[_strings];
+          return strings === null ? false : _hasTableEntry(strings, key);
+        } else if (_isNumericKey(key)) {
+          let nums = this[_nums];
+          return nums === null ? false : _hasTableEntry(nums, key);
+        } else {
+          return this[_containsKey](key);
         }
-        return dart.as(list, DoubleLinkedQueue$(E));
-      }
-      get length() {
-        return this[_elementCount];
       }
-      addLast(value) {
-        this[_sentinel].prepend(value);
-        this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
+      [_containsKey](key) {
+        let rest = this[_rest];
+        if (rest === null)
+          return false;
+        let bucket = this[_getBucket](rest, key);
+        return dart.notNull(this[_findBucketIndex](bucket, key)) >= 0;
       }
-      addFirst(value) {
-        this[_sentinel].append(value);
-        this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
+      containsValue(value) {
+        return this[_computeKeys]().any(((each) => dart.equals(this.get(each), value)).bind(this));
       }
-      add(value) {
-        this[_sentinel].prepend(value);
-        this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
+      addAll(other) {
+        other.forEach(((key, value) => {
+          this.set(key, value);
+        }).bind(this));
       }
-      addAll(iterable) {
-        for (let value of iterable) {
-          this[_sentinel].prepend(value);
-          this[_elementCount] = dart.notNull(this[_elementCount]) + 1;
+      get(key) {
+        if (_isStringKey(key)) {
+          let strings = this[_strings];
+          return dart.as(strings === null ? null : _getTableEntry(strings, key), V);
+        } else if (_isNumericKey(key)) {
+          let nums = this[_nums];
+          return dart.as(nums === null ? null : _getTableEntry(nums, key), V);
+        } else {
+          return this[_get](key);
         }
       }
-      removeLast() {
-        let result = this[_sentinel][_previous].remove();
-        this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
-        return result;
-      }
-      removeFirst() {
-        let result = this[_sentinel][_next].remove();
-        this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
-        return result;
+      [_get](key) {
+        let rest = this[_rest];
+        if (rest === null)
+          return null;
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
+        return dart.as(dart.notNull(index) < 0 ? null : bucket[dart.notNull(index) + 1], V);
       }
-      remove(o) {
-        let entry = this[_sentinel][_next];
-        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
-          if (dart.equals(entry.element, o)) {
-            entry.remove();
-            this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
-            return true;
-          }
-          entry = entry[_next];
+      set(key, value) {
+        if (_isStringKey(key)) {
+          let strings = this[_strings];
+          if (strings === null)
+            this[_strings] = strings = _newHashTable();
+          this[_addHashTableEntry](strings, key, value);
+        } else if (_isNumericKey(key)) {
+          let nums = this[_nums];
+          if (nums === null)
+            this[_nums] = nums = _newHashTable();
+          this[_addHashTableEntry](nums, key, value);
+        } else {
+          this[_set](key, value);
         }
-        return false;
       }
-      [_filter](test, removeMatching) {
-        let entry = this[_sentinel][_next];
-        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
-          let next = entry[_next];
-          if (core.identical(removeMatching, test(entry.element))) {
-            entry.remove();
-            this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
+      [_set](key, value) {
+        let rest = this[_rest];
+        if (rest === null)
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](key);
+        let bucket = rest[hash];
+        if (bucket === null) {
+          _setTableEntry(rest, hash, [key, value]);
+          this[_length] = dart.notNull(this[_length]) + 1;
+          this[_keys] = null;
+        } else {
+          let index = this[_findBucketIndex](bucket, key);
+          if (dart.notNull(index) >= 0) {
+            bucket[dart.notNull(index) + 1] = value;
+          } else {
+            bucket.push(key, value);
+            this[_length] = dart.notNull(this[_length]) + 1;
+            this[_keys] = null;
           }
-          entry = next;
         }
       }
-      removeWhere(test) {
-        this[_filter](test, true);
-      }
-      retainWhere(test) {
-        this[_filter](test, false);
+      putIfAbsent(key, ifAbsent) {
+        if (this.containsKey(key))
+          return this.get(key);
+        let value = ifAbsent();
+        this.set(key, value);
+        return value;
       }
-      get first() {
-        return this[_sentinel][_next].element;
+      remove(key) {
+        if (_isStringKey(key)) {
+          return this[_removeHashTableEntry](this[_strings], key);
+        } else if (_isNumericKey(key)) {
+          return this[_removeHashTableEntry](this[_nums], key);
+        } else {
+          return this[_remove](key);
+        }
       }
-      get last() {
-        return this[_sentinel][_previous].element;
+      [_remove](key) {
+        let rest = this[_rest];
+        if (rest === null)
+          return null;
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
+        if (dart.notNull(index) < 0)
+          return null;
+        this[_length] = dart.notNull(this[_length]) - 1;
+        this[_keys] = null;
+        return dart.as(bucket.splice(index, 2)[1], V);
       }
-      get single() {
-        if (core.identical(this[_sentinel][_next], this[_sentinel][_previous])) {
-          return this[_sentinel][_next].element;
+      clear() {
+        if (dart.notNull(this[_length]) > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_keys] = null;
+          this[_length] = 0;
         }
-        throw _internal.IterableElementError.tooMany();
       }
-      lastEntry() {
-        return this[_sentinel].previousEntry();
-      }
-      firstEntry() {
-        return this[_sentinel].nextEntry();
-      }
-      get isEmpty() {
-        return core.identical(this[_sentinel][_next], this[_sentinel]);
+      forEach(action) {
+        let keys = this[_computeKeys]();
+        for (let i = 0, length = keys.length; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let key = keys[i];
+          action(dart.as(key, K), this.get(key));
+          if (keys !== this[_keys]) {
+            throw new core.ConcurrentModificationError(this);
+          }
+        }
       }
-      clear() {
-        this[_sentinel][_next] = this[_sentinel];
-        this[_sentinel][_previous] = this[_sentinel];
-        this[_elementCount] = 0;
+      [_computeKeys]() {
+        if (this[_keys] !== null)
+          return this[_keys];
+        let result = new core.List(this[_length]);
+        let index = 0;
+        let strings = this[_strings];
+        if (strings !== null) {
+          let names = Object.getOwnPropertyNames(strings);
+          let entries = names.length;
+          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
+            let key = names[i];
+            result[index] = key;
+            index = dart.notNull(index) + 1;
+          }
+        }
+        let nums = this[_nums];
+        if (nums !== null) {
+          let names = Object.getOwnPropertyNames(nums);
+          let entries = names.length;
+          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
+            let key = +names[i];
+            result[index] = key;
+            index = dart.notNull(index) + 1;
+          }
+        }
+        let rest = this[_rest];
+        if (rest !== null) {
+          let names = Object.getOwnPropertyNames(rest);
+          let entries = names.length;
+          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
+            let key = names[i];
+            let bucket = rest[key];
+            let length = bucket.length;
+            for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
+              let key = bucket[i];
+              result[index] = key;
+              index = dart.notNull(index) + 1;
+            }
+          }
+        }
+        dart.assert(index === this[_length]);
+        return this[_keys] = result;
       }
-      forEachEntry(f) {
-        let entry = this[_sentinel][_next];
-        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
-          let nextEntry = entry[_next];
-          f(entry);
-          entry = nextEntry;
+      [_addHashTableEntry](table, key, value) {
+        if (!dart.notNull(_hasTableEntry(table, key))) {
+          this[_length] = dart.notNull(this[_length]) + 1;
+          this[_keys] = null;
         }
+        _setTableEntry(table, key, value);
       }
-      get iterator() {
-        return new _DoubleLinkedQueueIterator(this[_sentinel]);
+      [_removeHashTableEntry](table, key) {
+        if (dart.notNull(table !== null) && dart.notNull(_hasTableEntry(table, key))) {
+          let value = dart.as(_getTableEntry(table, key), V);
+          _deleteTableEntry(table, key);
+          this[_length] = dart.notNull(this[_length]) - 1;
+          this[_keys] = null;
+          return value;
+        } else {
+          return null;
+        }
       }
-      toString() {
-        return IterableBase.iterableToFullString(this, '{', '}');
+      static [_isStringKey](key) {
+        return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
       }
-    }
-    dart.defineNamedConstructor(DoubleLinkedQueue, 'from');
-    return DoubleLinkedQueue;
-  });
-  let DoubleLinkedQueue = DoubleLinkedQueue$(dynamic);
-  let _nextEntry = Symbol('_nextEntry');
-  let _DoubleLinkedQueueIterator$ = dart.generic(function(E) {
-    class _DoubleLinkedQueueIterator extends dart.Object {
-      _DoubleLinkedQueueIterator(sentinel) {
-        this[_sentinel] = sentinel;
-        this[_nextEntry] = sentinel[_next];
-        this[_current] = null;
+      static [_isNumericKey](key) {
+        return dart.notNull(dart.is(key, core.num)) && (key & 0x3ffffff) === key;
       }
-      moveNext() {
-        if (!dart.notNull(core.identical(this[_nextEntry], this[_sentinel]))) {
-          this[_current] = this[_nextEntry][_element];
-          this[_nextEntry] = this[_nextEntry][_next];
-          return true;
-        }
-        this[_current] = null;
-        this[_nextEntry] = this[_sentinel] = null;
-        return false;
+      [_computeHashCode](key) {
+        return dart.dload(key, 'hashCode') & 0x3ffffff;
       }
-      get current() {
-        return this[_current];
+      static [_hasTableEntry](table, key) {
+        let entry = table[key];
+        return entry !== null;
       }
-    }
-    return _DoubleLinkedQueueIterator;
-  });
-  let _DoubleLinkedQueueIterator = _DoubleLinkedQueueIterator$(dynamic);
-  let _head = Symbol('_head');
-  let _tail = Symbol('_tail');
-  let _table = Symbol('_table');
-  let _checkModification = Symbol('_checkModification');
-  let _writeToList = Symbol('_writeToList');
-  let _preGrow = Symbol('_preGrow');
-  let _grow = Symbol('_grow');
-  let _isPowerOf2 = Symbol('_isPowerOf2');
-  let _nextPowerOf2 = Symbol('_nextPowerOf2');
-  let ListQueue$ = dart.generic(function(E) {
-    class ListQueue extends IterableBase$(E) {
-      ListQueue(initialCapacity) {
-        if (initialCapacity === void 0)
-          initialCapacity = null;
-        this[_head] = 0;
-        this[_tail] = 0;
-        this[_table] = null;
-        this[_modificationCount] = 0;
-        super.IterableBase();
-        if (initialCapacity === null || dart.notNull(initialCapacity) < dart.notNull(_INITIAL_CAPACITY)) {
-          initialCapacity = _INITIAL_CAPACITY;
-        } else if (!dart.notNull(_isPowerOf2(initialCapacity))) {
-          initialCapacity = _nextPowerOf2(initialCapacity);
-        }
-        dart.assert(_isPowerOf2(initialCapacity));
-        this[_table] = new core.List(initialCapacity);
+      static [_getTableEntry](table, key) {
+        let entry = table[key];
+        return entry === table ? null : entry;
       }
-      ListQueue$from(elements) {
-        if (dart.is(elements, core.List)) {
-          let length = elements.length;
-          let queue = dart.as(new ListQueue(dart.notNull(length) + 1), ListQueue$(E));
-          dart.assert(dart.notNull(queue[_table].length) > dart.notNull(length));
-          let sourceList = elements;
-          queue[_table].setRange(0, length, dart.as(sourceList, core.Iterable$(E)), 0);
-          queue[_tail] = length;
-          return queue;
+      static [_setTableEntry](table, key, value) {
+        if (value === null) {
+          table[key] = table;
         } else {
-          let capacity = _INITIAL_CAPACITY;
-          if (dart.is(elements, _internal.EfficientLength)) {
-            capacity = elements.length;
-          }
-          let result = new ListQueue(capacity);
-          for (let element of elements) {
-            result.addLast(element);
-          }
-          return result;
+          table[key] = value;
         }
       }
-      get iterator() {
-        return new _ListQueueIterator(this);
+      static [_deleteTableEntry](table, key) {
+        delete table[key];
       }
-      forEach(action) {
-        let modificationCount = this[_modificationCount];
-        for (let i = this[_head]; i !== this[_tail]; i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1) {
-          action(this[_table].get(i));
-          this[_checkModification](modificationCount);
+      [_getBucket](table, key) {
+        let hash = this[_computeHashCode](key);
+        return dart.as(table[hash], core.List);
+      }
+      [_findBucketIndex](bucket, key) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
+          if (dart.equals(bucket[i], key))
+            return i;
         }
+        return -1;
       }
-      get isEmpty() {
-        return this[_head] === this[_tail];
+      static [_newHashTable]() {
+        let table = Object.create(null);
+        let temporaryKey = '<non-identifier-key>';
+        _setTableEntry(table, temporaryKey, table);
+        _deleteTableEntry(table, temporaryKey);
+        return table;
       }
-      get length() {
-        return dart.notNull(this[_tail]) - dart.notNull(this[_head]) & dart.notNull(this[_table].length) - 1;
+    }
+    return _HashMap;
+  });
+  let _HashMap = _HashMap$(dart.dynamic, dart.dynamic);
+  let _IdentityHashMap$ = dart.generic(function(K, V) {
+    class _IdentityHashMap extends _HashMap$(K, V) {
+      [_computeHashCode](key) {
+        return core.identityHashCode(key) & 0x3ffffff;
       }
-      get first() {
-        if (this[_head] === this[_tail])
-          throw _internal.IterableElementError.noElement();
-        return this[_table].get(this[_head]);
+      [_findBucketIndex](bucket, key) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
+          if (core.identical(bucket[i], key))
+            return i;
+        }
+        return -1;
       }
-      get last() {
-        if (this[_head] === this[_tail])
-          throw _internal.IterableElementError.noElement();
-        return this[_table].get(dart.notNull(this[_tail]) - 1 & dart.notNull(this[_table].length) - 1);
+    }
+    return _IdentityHashMap;
+  });
+  let _IdentityHashMap = _IdentityHashMap$(dart.dynamic, dart.dynamic);
+  let _equals = Symbol('_equals');
+  let _hashCode = Symbol('_hashCode');
+  let _CustomHashMap$ = dart.generic(function(K, V) {
+    class _CustomHashMap extends _HashMap$(K, V) {
+      _CustomHashMap($_equals, $_hashCode, validKey) {
+        this[_equals] = $_equals;
+        this[_hashCode] = $_hashCode;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
+        super._HashMap();
       }
-      get single() {
-        if (this[_head] === this[_tail])
-          throw _internal.IterableElementError.noElement();
-        if (dart.notNull(this.length) > 1)
-          throw _internal.IterableElementError.tooMany();
-        return this[_table].get(this[_head]);
+      get(key) {
+        if (!dart.notNull(this[_validKey](key)))
+          return null;
+        return super._get(key);
       }
-      elementAt(index) {
-        core.RangeError.checkValidIndex(index, this);
-        return this[_table].get(dart.notNull(this[_head]) + dart.notNull(index) & dart.notNull(this[_table].length) - 1);
+      set(key, value) {
+        super._set(key, value);
       }
-      toList(opt$) {
-        let growable = opt$.growable === void 0 ? true : opt$.growable;
-        let list = null;
-        if (growable) {
-          list = ((_) => {
-            _.length = this.length;
-            return _;
-          }).bind(this)(new core.List());
-        } else {
-          list = new core.List(this.length);
-        }
-        this[_writeToList](list);
-        return list;
-      }
-      add(element) {
-        this[_add](element);
-      }
-      addAll(elements) {
-        if (dart.is(elements, core.List)) {
-          let list = dart.as(elements, core.List);
-          let addCount = list.length;
-          let length = this.length;
-          if (dart.notNull(length) + dart.notNull(addCount) >= dart.notNull(this[_table].length)) {
-            this[_preGrow](dart.notNull(length) + dart.notNull(addCount));
-            this[_table].setRange(length, dart.notNull(length) + dart.notNull(addCount), dart.as(list, core.Iterable$(E)), 0);
-            this[_tail] = addCount;
-          } else {
-            let endSpace = dart.notNull(this[_table].length) - dart.notNull(this[_tail]);
-            if (dart.notNull(addCount) < dart.notNull(endSpace)) {
-              this[_table].setRange(this[_tail], dart.notNull(this[_tail]) + dart.notNull(addCount), dart.as(list, core.Iterable$(E)), 0);
-              this[_tail] = addCount;
-            } else {
-              let preSpace = dart.notNull(addCount) - dart.notNull(endSpace);
-              this[_table].setRange(this[_tail], dart.notNull(this[_tail]) + dart.notNull(endSpace), dart.as(list, core.Iterable$(E)), 0);
-              this[_table].setRange(0, preSpace, dart.as(list, core.Iterable$(E)), endSpace);
-              this[_tail] = preSpace;
-            }
-          }
-          this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        } else {
-          for (let element of elements)
-            this[_add](element);
-        }
-      }
-      remove(object) {
-        for (let i = this[_head]; i !== this[_tail]; i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1) {
-          let element = this[_table].get(i);
-          if (dart.equals(element, object)) {
-            this[_remove](i);
-            this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-            return true;
-          }
-        }
-        return false;
-      }
-      [_filterWhere](test, removeMatching) {
-        let index = this[_head];
-        let modificationCount = this[_modificationCount];
-        let i = this[_head];
-        while (i !== this[_tail]) {
-          let element = this[_table].get(i);
-          let remove = core.identical(removeMatching, test(element));
-          this[_checkModification](modificationCount);
-          if (remove) {
-            i = this[_remove](i);
-            modificationCount = this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-          } else {
-            i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1;
-          }
-        }
+      containsKey(key) {
+        if (!dart.notNull(this[_validKey](key)))
+          return false;
+        return super._containsKey(key);
       }
-      removeWhere(test) {
-        this[_filterWhere](test, true);
+      remove(key) {
+        if (!dart.notNull(this[_validKey](key)))
+          return null;
+        return super._remove(key);
       }
-      retainWhere(test) {
-        this[_filterWhere](test, false);
+      [_computeHashCode](key) {
+        return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
       }
-      clear() {
-        if (this[_head] !== this[_tail]) {
-          for (let i = this[_head]; i !== this[_tail]; i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1) {
-            this[_table].set(i, null);
-          }
-          this[_head] = this[_tail] = 0;
-          this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+      [_findBucketIndex](bucket, key) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = 2) {
+          if (this[_equals](dart.as(bucket[i], K), dart.as(key, K)))
+            return i;
         }
+        return -1;
       }
       toString() {
-        return IterableBase.iterableToFullString(this, "{", "}");
-      }
-      addLast(element) {
-        this[_add](element);
-      }
-      addFirst(element) {
-        this[_head] = dart.notNull(this[_head]) - 1 & dart.notNull(this[_table].length) - 1;
-        this[_table].set(this[_head], element);
-        if (this[_head] === this[_tail])
-          this[_grow]();
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-      }
-      removeFirst() {
-        if (this[_head] === this[_tail])
-          throw _internal.IterableElementError.noElement();
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        let result = this[_table].get(this[_head]);
-        this[_table].set(this[_head], null);
-        this[_head] = dart.notNull(this[_head]) + 1 & dart.notNull(this[_table].length) - 1;
-        return result;
+        return Maps.mapToString(this);
       }
-      removeLast() {
-        if (this[_head] === this[_tail])
-          throw _internal.IterableElementError.noElement();
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        this[_tail] = dart.notNull(this[_tail]) - 1 & dart.notNull(this[_table].length) - 1;
-        let result = this[_table].get(this[_tail]);
-        this[_table].set(this[_tail], null);
-        return result;
+    }
+    return _CustomHashMap;
+  });
+  let _CustomHashMap = _CustomHashMap$(dart.dynamic, dart.dynamic);
+  let HashMapKeyIterable$ = dart.generic(function(E) {
+    class HashMapKeyIterable extends IterableBase$(E) {
+      HashMapKeyIterable($_map) {
+        this[_map] = $_map;
+        super.IterableBase();
       }
-      static [_isPowerOf2](number) {
-        return (dart.notNull(number) & dart.notNull(number) - 1) === 0;
+      get length() {
+        return dart.as(dart.dload(this[_map], '_length'), core.int);
       }
-      static [_nextPowerOf2](number) {
-        dart.assert(dart.notNull(number) > 0);
-        number = (dart.notNull(number) << 1) - 1;
-        for (;;) {
-          let nextNumber = dart.notNull(number) & dart.notNull(number) - 1;
-          if (nextNumber === 0)
-            return number;
-          number = nextNumber;
-        }
+      get isEmpty() {
+        return dart.equals(dart.dload(this[_map], '_length'), 0);
       }
-      [_checkModification](expectedModificationCount) {
-        if (expectedModificationCount !== this[_modificationCount]) {
-          throw new core.ConcurrentModificationError(this);
-        }
+      get iterator() {
+        return new HashMapKeyIterator(this[_map], dart.as(dart.dinvoke(this[_map], '_computeKeys'), core.List));
       }
-      [_add](element) {
-        this[_table].set(this[_tail], element);
-        this[_tail] = dart.notNull(this[_tail]) + 1 & dart.notNull(this[_table].length) - 1;
-        if (this[_head] === this[_tail])
-          this[_grow]();
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+      contains(element) {
+        return dart.as(dart.dinvoke(this[_map], 'containsKey', element), core.bool);
       }
-      [_remove](offset) {
-        let mask = dart.notNull(this[_table].length) - 1;
-        let startDistance = dart.notNull(offset) - dart.notNull(this[_head]) & dart.notNull(mask);
-        let endDistance = dart.notNull(this[_tail]) - dart.notNull(offset) & dart.notNull(mask);
-        if (dart.notNull(startDistance) < dart.notNull(endDistance)) {
-          let i = offset;
-          while (i !== this[_head]) {
-            let prevOffset = dart.notNull(i) - 1 & dart.notNull(mask);
-            this[_table].set(i, this[_table].get(prevOffset));
-            i = prevOffset;
-          }
-          this[_table].set(this[_head], null);
-          this[_head] = dart.notNull(this[_head]) + 1 & dart.notNull(mask);
-          return dart.notNull(offset) + 1 & dart.notNull(mask);
-        } else {
-          this[_tail] = dart.notNull(this[_tail]) - 1 & dart.notNull(mask);
-          let i = offset;
-          while (i !== this[_tail]) {
-            let nextOffset = dart.notNull(i) + 1 & dart.notNull(mask);
-            this[_table].set(i, this[_table].get(nextOffset));
-            i = nextOffset;
+      forEach(f) {
+        let keys = dart.as(dart.dinvoke(this[_map], '_computeKeys'), core.List);
+        for (let i = 0, length = keys.length; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          f(dart.as(keys[i], E));
+          if (keys !== dart.dload(this[_map], '_keys')) {
+            throw new core.ConcurrentModificationError(this[_map]);
           }
-          this[_table].set(this[_tail], null);
-          return offset;
-        }
-      }
-      [_grow]() {
-        let newTable = new core.List(dart.notNull(this[_table].length) * 2);
-        let split = dart.notNull(this[_table].length) - dart.notNull(this[_head]);
-        newTable.setRange(0, split, this[_table], this[_head]);
-        newTable.setRange(split, dart.notNull(split) + dart.notNull(this[_head]), this[_table], 0);
-        this[_head] = 0;
-        this[_tail] = this[_table].length;
-        this[_table] = newTable;
-      }
-      [_writeToList](target) {
-        dart.assert(dart.notNull(target.length) >= dart.notNull(this.length));
-        if (dart.notNull(this[_head]) <= dart.notNull(this[_tail])) {
-          let length = dart.notNull(this[_tail]) - dart.notNull(this[_head]);
-          target.setRange(0, length, this[_table], this[_head]);
-          return length;
-        } else {
-          let firstPartSize = dart.notNull(this[_table].length) - dart.notNull(this[_head]);
-          target.setRange(0, firstPartSize, this[_table], this[_head]);
-          target.setRange(firstPartSize, dart.notNull(firstPartSize) + dart.notNull(this[_tail]), this[_table], 0);
-          return dart.notNull(this[_tail]) + dart.notNull(firstPartSize);
         }
       }
-      [_preGrow](newElementCount) {
-        dart.assert(dart.notNull(newElementCount) >= dart.notNull(this.length));
-        newElementCount = dart.notNull(newElementCount) >> 1;
-        let newCapacity = _nextPowerOf2(newElementCount);
-        let newTable = new core.List(newCapacity);
-        this[_tail] = this[_writeToList](newTable);
-        this[_table] = newTable;
-        this[_head] = 0;
-      }
     }
-    dart.defineNamedConstructor(ListQueue, 'from');
-    ListQueue._INITIAL_CAPACITY = 8;
-    return ListQueue;
+    return HashMapKeyIterable;
   });
-  let ListQueue = ListQueue$(dynamic);
-  let _queue = Symbol('_queue');
-  let _end = Symbol('_end');
-  let _position = Symbol('_position');
-  let _ListQueueIterator$ = dart.generic(function(E) {
-    class _ListQueueIterator extends dart.Object {
-      _ListQueueIterator(queue) {
-        this[_queue] = queue;
-        this[_end] = queue[_tail];
-        this[_modificationCount] = queue[_modificationCount];
-        this[_position] = queue[_head];
+  let HashMapKeyIterable = HashMapKeyIterable$(dart.dynamic);
+  let _offset = Symbol('_offset');
+  let HashMapKeyIterator$ = dart.generic(function(E) {
+    class HashMapKeyIterator extends core.Object {
+      HashMapKeyIterator($_map, $_keys) {
+        this[_map] = $_map;
+        this[_keys] = $_keys;
+        this[_offset] = 0;
         this[_current] = null;
       }
       get current() {
         return this[_current];
       }
       moveNext() {
-        this[_queue]._checkModification(this[_modificationCount]);
-        if (this[_position] === this[_end]) {
+        let keys = this[_keys];
+        let offset = this[_offset];
+        if (keys !== dart.dload(this[_map], '_keys')) {
+          throw new core.ConcurrentModificationError(this[_map]);
+        } else if (dart.notNull(offset) >= keys.length) {
           this[_current] = null;
           return false;
+        } else {
+          this[_current] = dart.as(keys[offset], E);
+          this[_offset] = dart.notNull(offset) + 1;
+          return true;
         }
-        this[_current] = dart.as(this[_queue][_table].get(this[_position]), E);
-        this[_position] = dart.notNull(this[_position]) + 1 & dart.notNull(this[_queue][_table].length) - 1;
-        return true;
       }
     }
-    return _ListQueueIterator;
+    return HashMapKeyIterator;
   });
-  let _ListQueueIterator = _ListQueueIterator$(dynamic);
-  let SetMixin$ = dart.generic(function(E) {
-    class SetMixin extends dart.Object {
-      get isEmpty() {
-        return this.length === 0;
-      }
-      get isNotEmpty() {
-        return this.length !== 0;
-      }
-      clear() {
-        this.removeAll(this.toList());
+  let HashMapKeyIterator = HashMapKeyIterator$(dart.dynamic);
+  let _modifications = Symbol('_modifications');
+  let _value = Symbol('_value');
+  let _newLinkedCell = Symbol('_newLinkedCell');
+  let _unlinkCell = Symbol('_unlinkCell');
+  let _modified = Symbol('_modified');
+  let _key = Symbol('_key');
+  let _LinkedHashMap$ = dart.generic(function(K, V) {
+    class _LinkedHashMap extends core.Object {
+      _LinkedHashMap() {
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_first] = null;
+        this[_last] = null;
+        this[_modifications] = 0;
       }
-      addAll(elements) {
-        for (let element of elements)
-          this.add(element);
+      get length() {
+        return this[_length];
       }
-      removeAll(elements) {
-        for (let element of elements)
-          this.remove(element);
+      get isEmpty() {
+        return this[_length] === 0;
       }
-      retainAll(elements) {
-        let toRemove = this.toSet();
-        for (let o of elements) {
-          toRemove.remove(o);
-        }
-        this.removeAll(toRemove);
+      get isNotEmpty() {
+        return !dart.notNull(this.isEmpty);
       }
-      removeWhere(test) {
-        let toRemove = new List.from([]);
-        for (let element of this) {
-          if (test(element))
-            toRemove.add(element);
-        }
-        this.removeAll(dart.as(toRemove, core.Iterable$(core.Object)));
+      get keys() {
+        return new LinkedHashMapKeyIterable(this);
       }
-      retainWhere(test) {
-        let toRemove = new List.from([]);
-        for (let element of this) {
-          if (!dart.notNull(test(element)))
-            toRemove.add(element);
-        }
-        this.removeAll(dart.as(toRemove, core.Iterable$(core.Object)));
+      get values() {
+        return new _internal.MappedIterable(this.keys, ((each) => this.get(each)).bind(this));
       }
-      containsAll(other) {
-        for (let o of other) {
-          if (!dart.notNull(this.contains(o)))
+      containsKey(key) {
+        if (_isStringKey(key)) {
+          let strings = this[_strings];
+          if (strings === null)
             return false;
+          let cell = dart.as(_getTableEntry(strings, key), LinkedHashMapCell);
+          return cell !== null;
+        } else if (_isNumericKey(key)) {
+          let nums = this[_nums];
+          if (nums === null)
+            return false;
+          let cell = dart.as(_getTableEntry(nums, key), LinkedHashMapCell);
+          return cell !== null;
+        } else {
+          return this[_containsKey](key);
         }
-        return true;
-      }
-      union(other) {
-        return ((_) => {
-          _.addAll(other);
-          return _;
-        }).bind(this)(this.toSet());
-      }
-      intersection(other) {
-        let result = this.toSet();
-        for (let element of this) {
-          if (!dart.notNull(other.contains(element)))
-            result.remove(element);
-        }
-        return result;
-      }
-      difference(other) {
-        let result = this.toSet();
-        for (let element of this) {
-          if (other.contains(element))
-            result.remove(element);
-        }
-        return result;
-      }
-      toList(opt$) {
-        let growable = opt$.growable === void 0 ? true : opt$.growable;
-        let result = growable ? ((_) => {
-          _.length = this.length;
-          return _;
-        }).bind(this)(new core.List()) : new core.List(this.length);
-        let i = 0;
-        for (let element of this)
-          result.set((($tmp) => i = dart.notNull($tmp) + 1, $tmp)(i), element);
-        return result;
-      }
-      map(f) {
-        return new _internal.EfficientLengthMappedIterable(this, f);
-      }
-      get single() {
-        if (dart.notNull(this.length) > 1)
-          throw _internal.IterableElementError.tooMany();
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext()))
-          throw _internal.IterableElementError.noElement();
-        let result = dart.as(it.current, E);
-        return result;
       }
-      toString() {
-        return IterableBase.iterableToFullString(this, '{', '}');
-      }
-      where(f) {
-        return new _internal.WhereIterable(this, f);
+      [_containsKey](key) {
+        let rest = this[_rest];
+        if (rest === null)
+          return false;
+        let bucket = this[_getBucket](rest, key);
+        return dart.notNull(this[_findBucketIndex](bucket, key)) >= 0;
       }
-      expand(f) {
-        return new _internal.ExpandIterable(this, f);
+      containsValue(value) {
+        return this.keys.any(((each) => dart.equals(this.get(each), value)).bind(this));
       }
-      forEach(f) {
-        for (let element of this)
-          f(element);
+      addAll(other) {
+        other.forEach(((key, value) => {
+          this.set(key, value);
+        }).bind(this));
       }
-      reduce(combine) {
-        let iterator = this.iterator;
-        if (!dart.notNull(iterator.moveNext())) {
-          throw _internal.IterableElementError.noElement();
-        }
-        let value = iterator.current;
-        while (iterator.moveNext()) {
-          value = combine(value, iterator.current);
+      get(key) {
+        if (_isStringKey(key)) {
+          let strings = this[_strings];
+          if (strings === null)
+            return null;
+          let cell = dart.as(_getTableEntry(strings, key), LinkedHashMapCell);
+          return dart.as(cell === null ? null : cell[_value], V);
+        } else if (_isNumericKey(key)) {
+          let nums = this[_nums];
+          if (nums === null)
+            return null;
+          let cell = dart.as(_getTableEntry(nums, key), LinkedHashMapCell);
+          return dart.as(cell === null ? null : cell[_value], V);
+        } else {
+          return this[_get](key);
         }
-        return value;
       }
-      fold(initialValue, combine) {
-        let value = initialValue;
-        for (let element of this)
-          value = combine(value, element);
-        return value;
+      [_get](key) {
+        let rest = this[_rest];
+        if (rest === null)
+          return null;
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
+        if (dart.notNull(index) < 0)
+          return null;
+        let cell = dart.as(bucket[index], LinkedHashMapCell);
+        return dart.as(cell[_value], V);
       }
-      every(f) {
-        for (let element of this) {
-          if (!dart.notNull(f(element)))
-            return false;
+      set(key, value) {
+        if (_isStringKey(key)) {
+          let strings = this[_strings];
+          if (strings === null)
+            this[_strings] = strings = _newHashTable();
+          this[_addHashTableEntry](strings, key, value);
+        } else if (_isNumericKey(key)) {
+          let nums = this[_nums];
+          if (nums === null)
+            this[_nums] = nums = _newHashTable();
+          this[_addHashTableEntry](nums, key, value);
+        } else {
+          this[_set](key, value);
         }
-        return true;
       }
-      join(separator) {
-        if (separator === void 0)
-          separator = "";
-        let iterator = this.iterator;
-        if (!dart.notNull(iterator.moveNext()))
-          return "";
-        let buffer = new core.StringBuffer();
-        if (dart.notNull(separator === null) || dart.notNull(dart.equals(separator, ""))) {
-          do {
-            buffer.write(`${iterator.current}`);
-          } while (iterator.moveNext());
+      [_set](key, value) {
+        let rest = this[_rest];
+        if (rest === null)
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](key);
+        let bucket = rest[hash];
+        if (bucket === null) {
+          let cell = this[_newLinkedCell](key, value);
+          _setTableEntry(rest, hash, [cell]);
         } else {
-          buffer.write(`${iterator.current}`);
-          while (iterator.moveNext()) {
-            buffer.write(separator);
-            buffer.write(`${iterator.current}`);
+          let index = this[_findBucketIndex](bucket, key);
+          if (dart.notNull(index) >= 0) {
+            let cell = dart.as(bucket[index], LinkedHashMapCell);
+            cell[_value] = value;
+          } else {
+            let cell = this[_newLinkedCell](key, value);
+            bucket.push(cell);
           }
         }
-        return buffer.toString();
-      }
-      any(test) {
-        for (let element of this) {
-          if (test(element))
-            return true;
-        }
-        return false;
       }
-      take(n) {
-        return new _internal.TakeIterable(this, n);
+      putIfAbsent(key, ifAbsent) {
+        if (this.containsKey(key))
+          return this.get(key);
+        let value = ifAbsent();
+        this.set(key, value);
+        return value;
       }
-      takeWhile(test) {
-        return new _internal.TakeWhileIterable(this, test);
+      remove(key) {
+        if (_isStringKey(key)) {
+          return this[_removeHashTableEntry](this[_strings], key);
+        } else if (_isNumericKey(key)) {
+          return this[_removeHashTableEntry](this[_nums], key);
+        } else {
+          return this[_remove](key);
+        }
       }
-      skip(n) {
-        return new _internal.SkipIterable(this, n);
+      [_remove](key) {
+        let rest = this[_rest];
+        if (rest === null)
+          return null;
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
+        if (dart.notNull(index) < 0)
+          return null;
+        let cell = dart.as(bucket.splice(index, 1)[0], LinkedHashMapCell);
+        this[_unlinkCell](cell);
+        return dart.as(cell[_value], V);
       }
-      skipWhile(test) {
-        return new _internal.SkipWhileIterable(this, test);
+      clear() {
+        if (dart.notNull(this[_length]) > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_first] = this[_last] = null;
+          this[_length] = 0;
+          this[_modified]();
+        }
       }
-      get first() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext())) {
-          throw _internal.IterableElementError.noElement();
+      forEach(action) {
+        let cell = this[_first];
+        let modifications = this[_modifications];
+        while (cell !== null) {
+          action(dart.as(cell[_key], K), dart.as(cell[_value], V));
+          if (modifications !== this[_modifications]) {
+            throw new core.ConcurrentModificationError(this);
+          }
+          cell = cell[_next];
         }
-        return dart.as(it.current, E);
       }
-      get last() {
-        let it = this.iterator;
-        if (!dart.notNull(it.moveNext())) {
-          throw _internal.IterableElementError.noElement();
+      [_addHashTableEntry](table, key, value) {
+        let cell = dart.as(_getTableEntry(table, key), LinkedHashMapCell);
+        if (cell === null) {
+          _setTableEntry(table, key, this[_newLinkedCell](key, value));
+        } else {
+          cell[_value] = value;
         }
-        let result = null;
-        do {
-          result = dart.as(it.current, E);
-        } while (it.moveNext());
-        return result;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        for (let element of this) {
-          if (test(element))
-            return element;
+      [_removeHashTableEntry](table, key) {
+        if (table === null)
+          return null;
+        let cell = dart.as(_getTableEntry(table, key), LinkedHashMapCell);
+        if (cell === null)
+          return null;
+        this[_unlinkCell](cell);
+        _deleteTableEntry(table, key);
+        return dart.as(cell[_value], V);
+      }
+      [_modified]() {
+        this[_modifications] = dart.notNull(this[_modifications]) + 1 & 67108863;
+      }
+      [_newLinkedCell](key, value) {
+        let cell = new LinkedHashMapCell(key, value);
+        if (this[_first] === null) {
+          this[_first] = this[_last] = cell;
+        } else {
+          let last = this[_last];
+          cell[_previous] = last;
+          this[_last] = last[_next] = cell;
         }
-        if (orElse !== null)
-          return orElse();
-        throw _internal.IterableElementError.noElement();
+        this[_length] = dart.notNull(this[_length]) + 1;
+        this[_modified]();
+        return cell;
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$.orElse === void 0 ? null : opt$.orElse;
-        let result = null;
-        let foundMatching = false;
-        for (let element of this) {
-          if (test(element)) {
-            result = element;
-            foundMatching = true;
-          }
+      [_unlinkCell](cell) {
+        let previous = cell[_previous];
+        let next = cell[_next];
+        if (previous === null) {
+          dart.assert(dart.equals(cell, this[_first]));
+          this[_first] = next;
+        } else {
+          previous[_next] = next;
         }
-        if (foundMatching)
-          return result;
-        if (orElse !== null)
-          return orElse();
-        throw _internal.IterableElementError.noElement();
+        if (next === null) {
+          dart.assert(dart.equals(cell, this[_last]));
+          this[_last] = previous;
+        } else {
+          next[_previous] = previous;
+        }
+        this[_length] = dart.notNull(this[_length]) - 1;
+        this[_modified]();
       }
-      singleWhere(test) {
-        let result = null;
-        let foundMatching = false;
-        for (let element of this) {
-          if (test(element)) {
-            if (foundMatching) {
-              throw _internal.IterableElementError.tooMany();
-            }
-            result = element;
-            foundMatching = true;
-          }
+      static [_isStringKey](key) {
+        return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
+      }
+      static [_isNumericKey](key) {
+        return dart.notNull(dart.is(key, core.num)) && (key & 0x3ffffff) === key;
+      }
+      [_computeHashCode](key) {
+        return dart.dload(key, 'hashCode') & 0x3ffffff;
+      }
+      static [_getTableEntry](table, key) {
+        return table[key];
+      }
+      static [_setTableEntry](table, key, value) {
+        dart.assert(value !== null);
+        table[key] = value;
+      }
+      static [_deleteTableEntry](table, key) {
+        delete table[key];
+      }
+      [_getBucket](table, key) {
+        let hash = this[_computeHashCode](key);
+        return dart.as(table[hash], core.List);
+      }
+      [_findBucketIndex](bucket, key) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let cell = dart.as(bucket[i], LinkedHashMapCell);
+          if (dart.equals(cell[_key], key))
+            return i;
         }
-        if (foundMatching)
-          return result;
-        throw _internal.IterableElementError.noElement();
+        return -1;
       }
-      elementAt(index) {
-        if (!(typeof index == number))
-          throw new core.ArgumentError.notNull("index");
-        core.RangeError.checkNotNegative(index, "index");
-        let elementIndex = 0;
-        for (let element of this) {
-          if (index === elementIndex)
-            return element;
-          elementIndex = dart.notNull(elementIndex) + 1;
+      static [_newHashTable]() {
+        let table = Object.create(null);
+        let temporaryKey = '<non-identifier-key>';
+        _setTableEntry(table, temporaryKey, table);
+        _deleteTableEntry(table, temporaryKey);
+        return table;
+      }
+      toString() {
+        return Maps.mapToString(this);
+      }
+    }
+    return _LinkedHashMap;
+  });
+  let _LinkedHashMap = _LinkedHashMap$(dart.dynamic, dart.dynamic);
+  let _LinkedIdentityHashMap$ = dart.generic(function(K, V) {
+    class _LinkedIdentityHashMap extends _LinkedHashMap$(K, V) {
+      [_computeHashCode](key) {
+        return core.identityHashCode(key) & 0x3ffffff;
+      }
+      [_findBucketIndex](bucket, key) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let cell = dart.as(bucket[i], LinkedHashMapCell);
+          if (core.identical(cell[_key], key))
+            return i;
         }
-        throw new core.RangeError.index(index, this, "index", null, elementIndex);
+        return -1;
       }
     }
-    return SetMixin;
+    return _LinkedIdentityHashMap;
   });
-  let SetMixin = SetMixin$(dynamic);
-  let SetBase$ = dart.generic(function(E) {
-    class SetBase extends SetMixin$(E) {
-      static setToString(set) {
-        return IterableBase.iterableToFullString(set, '{', '}');
+  let _LinkedIdentityHashMap = _LinkedIdentityHashMap$(dart.dynamic, dart.dynamic);
+  let _LinkedCustomHashMap$ = dart.generic(function(K, V) {
+    class _LinkedCustomHashMap extends _LinkedHashMap$(K, V) {
+      _LinkedCustomHashMap($_equals, $_hashCode, validKey) {
+        this[_equals] = $_equals;
+        this[_hashCode] = $_hashCode;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
+        super._LinkedHashMap();
+      }
+      get(key) {
+        if (!dart.notNull(this[_validKey](key)))
+          return null;
+        return super._get(key);
+      }
+      set(key, value) {
+        super._set(key, value);
+      }
+      containsKey(key) {
+        if (!dart.notNull(this[_validKey](key)))
+          return false;
+        return super._containsKey(key);
+      }
+      remove(key) {
+        if (!dart.notNull(this[_validKey](key)))
+          return null;
+        return super._remove(key);
+      }
+      [_computeHashCode](key) {
+        return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
+      }
+      [_findBucketIndex](bucket, key) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let cell = dart.as(bucket[i], LinkedHashMapCell);
+          if (this[_equals](dart.as(cell[_key], K), dart.as(key, K)))
+            return i;
+        }
+        return -1;
       }
     }
-    return SetBase;
+    return _LinkedCustomHashMap;
   });
-  let SetBase = SetBase$(dynamic);
-  let _SplayTreeNode$ = dart.generic(function(K) {
-    class _SplayTreeNode extends dart.Object {
-      _SplayTreeNode(key) {
-        this.key = key;
-        this.left = null;
-        this.right = null;
+  let _LinkedCustomHashMap = _LinkedCustomHashMap$(dart.dynamic, dart.dynamic);
+  class LinkedHashMapCell extends core.Object {
+    LinkedHashMapCell($_key, $_value) {
+      this[_key] = $_key;
+      this[_value] = $_value;
+      this[_next] = null;
+      this[_previous] = null;
+    }
+  }
+  let LinkedHashMapKeyIterable$ = dart.generic(function(E) {
+    class LinkedHashMapKeyIterable extends IterableBase$(E) {
+      LinkedHashMapKeyIterable($_map) {
+        this[_map] = $_map;
+        super.IterableBase();
+      }
+      get length() {
+        return dart.as(dart.dload(this[_map], '_length'), core.int);
+      }
+      get isEmpty() {
+        return dart.equals(dart.dload(this[_map], '_length'), 0);
+      }
+      get iterator() {
+        return new LinkedHashMapKeyIterator(this[_map], dart.as(dart.dload(this[_map], '_modifications'), core.int));
+      }
+      contains(element) {
+        return dart.as(dart.dinvoke(this[_map], 'containsKey', element), core.bool);
+      }
+      forEach(f) {
+        let cell = dart.as(dart.dload(this[_map], '_first'), LinkedHashMapCell);
+        let modifications = dart.as(dart.dload(this[_map], '_modifications'), core.int);
+        while (cell !== null) {
+          f(dart.as(cell[_key], E));
+          if (modifications !== dart.dload(this[_map], '_modifications')) {
+            throw new core.ConcurrentModificationError(this[_map]);
+          }
+          cell = cell[_next];
+        }
       }
     }
-    return _SplayTreeNode;
+    return LinkedHashMapKeyIterable;
   });
-  let _SplayTreeNode = _SplayTreeNode$(dynamic);
-  let _SplayTreeMapNode$ = dart.generic(function(K, V) {
-    class _SplayTreeMapNode extends _SplayTreeNode$(K) {
-      _SplayTreeMapNode(key, value) {
-        this.value = value;
-        super._SplayTreeNode(key);
+  let LinkedHashMapKeyIterable = LinkedHashMapKeyIterable$(dart.dynamic);
+  let _cell = Symbol('_cell');
+  let LinkedHashMapKeyIterator$ = dart.generic(function(E) {
+    class LinkedHashMapKeyIterator extends core.Object {
+      LinkedHashMapKeyIterator($_map, $_modifications) {
+        this[_map] = $_map;
+        this[_modifications] = $_modifications;
+        this[_cell] = null;
+        this[_current] = null;
+        this[_cell] = dart.as(dart.dload(this[_map], '_first'), LinkedHashMapCell);
+      }
+      get current() {
+        return this[_current];
+      }
+      moveNext() {
+        if (this[_modifications] !== dart.dload(this[_map], '_modifications')) {
+          throw new core.ConcurrentModificationError(this[_map]);
+        } else if (this[_cell] === null) {
+          this[_current] = null;
+          return false;
+        } else {
+          this[_current] = dart.as(this[_cell][_key], E);
+          this[_cell] = this[_cell][_next];
+          return true;
+        }
       }
     }
-    return _SplayTreeMapNode;
+    return LinkedHashMapKeyIterator;
   });
-  let _SplayTreeMapNode = _SplayTreeMapNode$(dynamic, dynamic);
-  let _dummy = Symbol('_dummy');
-  let _root = Symbol('_root');
-  let _count = Symbol('_count');
-  let _splayCount = Symbol('_splayCount');
-  let _splay = Symbol('_splay');
-  let _compare = Symbol('_compare');
-  let _splayMin = Symbol('_splayMin');
-  let _splayMax = Symbol('_splayMax');
-  let _addNewRoot = Symbol('_addNewRoot');
-  let _clear = Symbol('_clear');
-  let _SplayTree$ = dart.generic(function(K) {
-    class _SplayTree extends dart.Object {
-      _SplayTree() {
-        this[_dummy] = new _SplayTreeNode(null);
-        this[_root] = null;
-        this[_count] = 0;
-        this[_modificationCount] = 0;
-        this[_splayCount] = 0;
+  let LinkedHashMapKeyIterator = LinkedHashMapKeyIterator$(dart.dynamic);
+  let _elements = Symbol('_elements');
+  let _computeElements = Symbol('_computeElements');
+  let _contains = Symbol('_contains');
+  let _lookup = Symbol('_lookup');
+  let _isStringElement = Symbol('_isStringElement');
+  let _isNumericElement = Symbol('_isNumericElement');
+  let _HashSet$ = dart.generic(function(E) {
+    class _HashSet extends _HashSetBase$(E) {
+      _HashSet() {
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_elements] = null;
+        super._HashSetBase();
       }
-      [_splay](key) {
-        if (this[_root] === null)
-          return -1;
-        let left = this[_dummy];
-        let right = this[_dummy];
-        let current = this[_root];
-        let comp = null;
-        while (true) {
-          comp = this[_compare](current.key, key);
-          if (dart.notNull(comp) > 0) {
-            if (current.left === null)
-              break;
-            comp = this[_compare](current.left.key, key);
-            if (dart.notNull(comp) > 0) {
-              let tmp = current.left;
-              current.left = tmp.right;
-              tmp.right = current;
-              current = tmp;
-              if (current.left === null)
-                break;
-            }
-            right.left = current;
-            right = current;
-            current = current.left;
-          } else if (dart.notNull(comp) < 0) {
-            if (current.right === null)
-              break;
-            comp = this[_compare](current.right.key, key);
-            if (dart.notNull(comp) < 0) {
-              let tmp = current.right;
-              current.right = tmp.left;
-              tmp.left = current;
-              current = tmp;
-              if (current.right === null)
-                break;
-            }
-            left.right = current;
-            left = current;
-            current = current.right;
-          } else {
-            break;
-          }
+      [_newSet]() {
+        return new _HashSet();
+      }
+      get iterator() {
+        return new HashSetIterator(this, this[_computeElements]());
+      }
+      get length() {
+        return this[_length];
+      }
+      get isEmpty() {
+        return this[_length] === 0;
+      }
+      get isNotEmpty() {
+        return !dart.notNull(this.isEmpty);
+      }
+      contains(object) {
+        if (_isStringElement(object)) {
+          let strings = this[_strings];
+          return strings === null ? false : _hasTableEntry(strings, object);
+        } else if (_isNumericElement(object)) {
+          let nums = this[_nums];
+          return nums === null ? false : _hasTableEntry(nums, object);
+        } else {
+          return this[_contains](object);
         }
-        left.right = current.left;
-        right.left = current.right;
-        current.left = this[_dummy].right;
-        current.right = this[_dummy].left;
-        this[_root] = current;
-        this[_dummy].right = null;
-        this[_dummy].left = null;
-        this[_splayCount] = dart.notNull(this[_splayCount]) + 1;
-        return comp;
       }
-      [_splayMin](node) {
-        let current = node;
-        while (current.left !== null) {
-          let left = current.left;
-          current.left = left.right;
-          left.right = current;
-          current = left;
+      [_contains](object) {
+        let rest = this[_rest];
+        if (rest === null)
+          return false;
+        let bucket = this[_getBucket](rest, object);
+        return dart.notNull(this[_findBucketIndex](bucket, object)) >= 0;
+      }
+      lookup(object) {
+        if (dart.notNull(_isStringElement(object)) || dart.notNull(_isNumericElement(object))) {
+          return dart.as(this.contains(object) ? object : null, E);
+        }
+        return this[_lookup](object);
+      }
+      [_lookup](object) {
+        let rest = this[_rest];
+        if (rest === null)
+          return null;
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
+        if (dart.notNull(index) < 0)
+          return null;
+        return dart.as(bucket.get(index), E);
+      }
+      add(element) {
+        if (_isStringElement(element)) {
+          let strings = this[_strings];
+          if (strings === null)
+            this[_strings] = strings = _newHashTable();
+          return this[_addHashTableEntry](strings, element);
+        } else if (_isNumericElement(element)) {
+          let nums = this[_nums];
+          if (nums === null)
+            this[_nums] = nums = _newHashTable();
+          return this[_addHashTableEntry](nums, element);
+        } else {
+          return this[_add](element);
+        }
+      }
+      [_add](element) {
+        let rest = this[_rest];
+        if (rest === null)
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](element);
+        let bucket = rest[hash];
+        if (bucket === null) {
+          _setTableEntry(rest, hash, [element]);
+        } else {
+          let index = this[_findBucketIndex](bucket, element);
+          if (dart.notNull(index) >= 0)
+            return false;
+          bucket.push(element);
+        }
+        this[_length] = dart.notNull(this[_length]) + 1;
+        this[_elements] = null;
+        return true;
+      }
+      addAll(objects) {
+        for (let each of objects) {
+          this.add(each);
         }
-        return dart.as(current, _SplayTreeNode$(K));
       }
-      [_splayMax](node) {
-        let current = node;
-        while (current.right !== null) {
-          let right = current.right;
-          current.right = right.left;
-          right.left = current;
-          current = right;
+      remove(object) {
+        if (_isStringElement(object)) {
+          return this[_removeHashTableEntry](this[_strings], object);
+        } else if (_isNumericElement(object)) {
+          return this[_removeHashTableEntry](this[_nums], object);
+        } else {
+          return this[_remove](object);
         }
-        return dart.as(current, _SplayTreeNode$(K));
       }
-      [_remove](key) {
-        if (this[_root] === null)
-          return null;
-        let comp = this[_splay](key);
-        if (comp !== 0)
-          return null;
-        let result = this[_root];
-        this[_count] = dart.notNull(this[_count]) - 1;
-        if (this[_root].left === null) {
-          this[_root] = this[_root].right;
-        } else {
-          let right = this[_root].right;
-          this[_root] = this[_splayMax](this[_root].left);
-          this[_root].right = right;
+      [_remove](object) {
+        let rest = this[_rest];
+        if (rest === null)
+          return false;
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
+        if (dart.notNull(index) < 0)
+          return false;
+        this[_length] = dart.notNull(this[_length]) - 1;
+        this[_elements] = null;
+        bucket.splice(index, 1);
+        return true;
+      }
+      clear() {
+        if (dart.notNull(this[_length]) > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_elements] = null;
+          this[_length] = 0;
         }
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        return result;
       }
-      [_addNewRoot](node, comp) {
-        this[_count] = dart.notNull(this[_count]) + 1;
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
-        if (this[_root] === null) {
-          this[_root] = node;
-          return;
+      [_computeElements]() {
+        if (this[_elements] !== null)
+          return this[_elements];
+        let result = new core.List(this[_length]);
+        let index = 0;
+        let strings = this[_strings];
+        if (strings !== null) {
+          let names = Object.getOwnPropertyNames(strings);
+          let entries = names.length;
+          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
+            let element = names[i];
+            result[index] = element;
+            index = dart.notNull(index) + 1;
+          }
         }
-        if (dart.notNull(comp) < 0) {
-          node.left = this[_root];
-          node.right = this[_root].right;
-          this[_root].right = null;
-        } else {
-          node.right = this[_root];
-          node.left = this[_root].left;
-          this[_root].left = null;
+        let nums = this[_nums];
+        if (nums !== null) {
+          let names = Object.getOwnPropertyNames(nums);
+          let entries = names.length;
+          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
+            let element = +names[i];
+            result[index] = element;
+            index = dart.notNull(index) + 1;
+          }
         }
-        this[_root] = node;
-      }
-      get [_first]() {
-        if (this[_root] === null)
-          return null;
-        this[_root] = this[_splayMin](this[_root]);
-        return this[_root];
+        let rest = this[_rest];
+        if (rest !== null) {
+          let names = Object.getOwnPropertyNames(rest);
+          let entries = names.length;
+          for (let i = 0; dart.notNull(i) < dart.notNull(entries); i = dart.notNull(i) + 1) {
+            let entry = names[i];
+            let bucket = rest[entry];
+            let length = bucket.length;
+            for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+              result[index] = bucket[i];
+              index = dart.notNull(index) + 1;
+            }
+          }
+        }
+        dart.assert(index === this[_length]);
+        return this[_elements] = result;
       }
-      get [_last]() {
-        if (this[_root] === null)
-          return null;
-        this[_root] = this[_splayMax](this[_root]);
-        return this[_root];
+      [_addHashTableEntry](table, element) {
+        if (_hasTableEntry(table, element))
+          return false;
+        _setTableEntry(table, element, 0);
+        this[_length] = dart.notNull(this[_length]) + 1;
+        this[_elements] = null;
+        return true;
       }
-      [_clear]() {
-        this[_root] = null;
-        this[_count] = 0;
-        this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
+      [_removeHashTableEntry](table, element) {
+        if (dart.notNull(table !== null) && dart.notNull(_hasTableEntry(table, element))) {
+          _deleteTableEntry(table, element);
+          this[_length] = dart.notNull(this[_length]) - 1;
+          this[_elements] = null;
+          return true;
+        } else {
+          return false;
+        }
       }
-    }
-    return _SplayTree;
-  });
-  let _SplayTree = _SplayTree$(dynamic);
-  let _TypeTest$ = dart.generic(function(T) {
-    class _TypeTest extends dart.Object {
-      test(v) {
-        return dart.is(v, T);
+      static [_isStringElement](element) {
+        return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
       }
-    }
-    return _TypeTest;
-  });
-  let _TypeTest = _TypeTest$(dynamic);
-  let _comparator = Symbol('_comparator');
-  let SplayTreeMap$ = dart.generic(function(K, V) {
-    class SplayTreeMap extends _SplayTree$(K) {
-      SplayTreeMap(compare, isValidKey) {
-        if (compare === void 0)
-          compare = null;
-        if (isValidKey === void 0)
-          isValidKey = null;
-        this[_comparator] = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
-        this[_validKey] = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, K), _Predicate);
-        super._SplayTree();
+      static [_isNumericElement](element) {
+        return dart.notNull(dart.is(element, core.num)) && (element & 0x3ffffff) === element;
       }
-      SplayTreeMap$from(other, compare, isValidKey) {
-        if (compare === void 0)
-          compare = null;
-        if (isValidKey === void 0)
-          isValidKey = null;
-        let result = new SplayTreeMap();
-        other.forEach((k, v) => {
-          result.set(k, dart.as(v, V));
-        });
-        return result;
+      [_computeHashCode](element) {
+        return dart.dload(element, 'hashCode') & 0x3ffffff;
       }
-      SplayTreeMap$fromIterable(iterable, opt$) {
-        let key = opt$.key === void 0 ? null : opt$.key;
-        let value = opt$.value === void 0 ? null : opt$.value;
-        let compare = opt$.compare === void 0 ? null : opt$.compare;
-        let isValidKey = opt$.isValidKey === void 0 ? null : opt$.isValidKey;
-        let map = new SplayTreeMap(compare, isValidKey);
-        Maps._fillMapWithMappedIterable(map, iterable, key, value);
-        return map;
+      static [_hasTableEntry](table, key) {
+        let entry = table[key];
+        return entry !== null;
       }
-      SplayTreeMap$fromIterables(keys, values, compare, isValidKey) {
-        if (compare === void 0)
-          compare = null;
-        if (isValidKey === void 0)
-          isValidKey = null;
-        let map = new SplayTreeMap(compare, isValidKey);
-        Maps._fillMapWithIterables(map, keys, values);
-        return map;
+      static [_setTableEntry](table, key, value) {
+        dart.assert(value !== null);
+        table[key] = value;
       }
-      [_compare](key1, key2) {
-        return this[_comparator](key1, key2);
+      static [_deleteTableEntry](table, key) {
+        delete table[key];
       }
-      SplayTreeMap$_internal() {
-        this[_comparator] = null;
-        this[_validKey] = null;
-        super._SplayTree();
+      [_getBucket](table, element) {
+        let hash = this[_computeHashCode](element);
+        return dart.as(table[hash], core.List);
       }
-      get(key) {
-        if (key === null)
-          throw new core.ArgumentError(key);
-        if (!dart.notNull(this[_validKey](key)))
-          return null;
-        if (this[_root] !== null) {
-          let comp = this[_splay](dart.as(key, K));
-          if (comp === 0) {
-            let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
-            return dart.as(mapRoot.value, V);
-          }
+      [_findBucketIndex](bucket, element) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          if (dart.equals(bucket[i], element))
+            return i;
         }
-        return null;
+        return -1;
       }
-      remove(key) {
-        if (!dart.notNull(this[_validKey](key)))
-          return null;
-        let mapRoot = dart.as(this[_remove](dart.as(key, K)), _SplayTreeMapNode);
-        if (mapRoot !== null)
-          return dart.as(mapRoot.value, V);
-        return null;
+      static [_newHashTable]() {
+        let table = Object.create(null);
+        let temporaryKey = '<non-identifier-key>';
+        _setTableEntry(table, temporaryKey, table);
+        _deleteTableEntry(table, temporaryKey);
+        return table;
       }
-      set(key, value) {
-        if (key === null)
-          throw new core.ArgumentError(key);
-        let comp = this[_splay](key);
-        if (comp === 0) {
-          let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
-          mapRoot.value = value;
-          return;
-        }
-        this[_addNewRoot](dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
+    }
+    return _HashSet;
+  });
+  let _HashSet = _HashSet$(dart.dynamic);
+  let _IdentityHashSet$ = dart.generic(function(E) {
+    class _IdentityHashSet extends _HashSet$(E) {
+      [_newSet]() {
+        return new _IdentityHashSet();
+      }
+      [_computeHashCode](key) {
+        return core.identityHashCode(key) & 0x3ffffff;
       }
-      putIfAbsent(key, ifAbsent) {
-        if (key === null)
-          throw new core.ArgumentError(key);
-        let comp = this[_splay](key);
-        if (comp === 0) {
-          let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
-          return dart.as(mapRoot.value, V);
-        }
-        let modificationCount = this[_modificationCount];
-        let splayCount = this[_splayCount];
-        let value = ifAbsent();
-        if (modificationCount !== this[_modificationCount]) {
-          throw new core.ConcurrentModificationError(this);
+      [_findBucketIndex](bucket, element) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          if (core.identical(bucket[i], element))
+            return i;
         }
-        if (splayCount !== this[_splayCount]) {
-          comp = this[_splay](key);
-          dart.assert(comp !== 0);
+        return -1;
+      }
+    }
+    return _IdentityHashSet;
+  });
+  let _IdentityHashSet = _IdentityHashSet$(dart.dynamic);
+  let _equality = Symbol('_equality');
+  let _hasher = Symbol('_hasher');
+  let _CustomHashSet$ = dart.generic(function(E) {
+    class _CustomHashSet extends _HashSet$(E) {
+      _CustomHashSet($_equality, $_hasher, validKey) {
+        this[_equality] = $_equality;
+        this[_hasher] = $_hasher;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
+        super._HashSet();
+      }
+      [_newSet]() {
+        return new _CustomHashSet(this[_equality], this[_hasher], this[_validKey]);
+      }
+      [_findBucketIndex](bucket, element) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          if (this[_equality](dart.as(bucket[i], E), dart.as(element, E)))
+            return i;
         }
-        this[_addNewRoot](dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
-        return value;
+        return -1;
       }
-      addAll(other) {
-        other.forEach(((key, value) => {
-          this.set(key, value);
-        }).bind(this));
+      [_computeHashCode](element) {
+        return this[_hasher](dart.as(element, E)) & 0x3ffffff;
       }
-      get isEmpty() {
-        return this[_root] === null;
+      add(object) {
+        return super._add(object);
       }
-      get isNotEmpty() {
-        return !dart.notNull(this.isEmpty);
+      contains(object) {
+        if (!dart.notNull(this[_validKey](object)))
+          return false;
+        return super._contains(object);
       }
-      forEach(f) {
-        let nodes = new _SplayTreeNodeIterator(this);
-        while (nodes.moveNext()) {
-          let node = dart.as(nodes.current, _SplayTreeMapNode$(K, V));
-          f(node.key, node.value);
-        }
+      lookup(object) {
+        if (!dart.notNull(this[_validKey](object)))
+          return null;
+        return super._lookup(object);
       }
-      get length() {
-        return this[_count];
+      remove(object) {
+        if (!dart.notNull(this[_validKey](object)))
+          return false;
+        return super._remove(object);
       }
-      clear() {
-        this[_clear]();
+    }
+    return _CustomHashSet;
+  });
+  let _CustomHashSet = _CustomHashSet$(dart.dynamic);
+  let HashSetIterator$ = dart.generic(function(E) {
+    class HashSetIterator extends core.Object {
+      HashSetIterator($_set, $_elements) {
+        this[_set] = $_set;
+        this[_elements] = $_elements;
+        this[_offset] = 0;
+        this[_current] = null;
       }
-      containsKey(key) {
-        return dart.notNull(this[_validKey](key)) && this[_splay](dart.as(key, K)) === 0;
+      get current() {
+        return this[_current];
       }
-      containsValue(value) {
-        let found = false;
-        let initialSplayCount = this[_splayCount];
-        // Function visit: (_SplayTreeMapNode<dynamic, dynamic>) → bool
-        function visit(node) {
-          while (node !== null) {
-            if (dart.equals(node.value, value))
-              return true;
-            if (initialSplayCount !== this[_splayCount]) {
-              throw new core.ConcurrentModificationError(this);
-            }
-            if (dart.notNull(node.right !== null) && dart.notNull(visit(dart.as(node.right, _SplayTreeMapNode))))
-              return true;
-            node = dart.as(node.left, _SplayTreeMapNode);
-          }
+      moveNext() {
+        let elements = this[_elements];
+        let offset = this[_offset];
+        if (elements !== dart.dload(this[_set], '_elements')) {
+          throw new core.ConcurrentModificationError(this[_set]);
+        } else if (dart.notNull(offset) >= elements.length) {
+          this[_current] = null;
           return false;
+        } else {
+          this[_current] = dart.as(elements[offset], E);
+          this[_offset] = dart.notNull(offset) + 1;
+          return true;
         }
-        return visit(dart.as(this[_root], _SplayTreeMapNode));
       }
-      get keys() {
-        return new _SplayTreeKeyIterable(this);
+    }
+    return HashSetIterator;
+  });
+  let HashSetIterator = HashSetIterator$(dart.dynamic);
+  let _unsupported = Symbol('_unsupported');
+  let _LinkedHashSet$ = dart.generic(function(E) {
+    class _LinkedHashSet extends _HashSetBase$(E) {
+      _LinkedHashSet() {
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_first] = null;
+        this[_last] = null;
+        this[_modifications] = 0;
+        super._HashSetBase();
       }
-      get values() {
-        return new _SplayTreeValueIterable(this);
+      [_newSet]() {
+        return new _LinkedHashSet();
       }
-      toString() {
-        return Maps.mapToString(this);
+      [_unsupported](operation) {
+        throw `LinkedHashSet: unsupported ${operation}`;
       }
-      firstKey() {
-        if (this[_root] === null)
-          return null;
-        return dart.as(this[_first].key, K);
+      get iterator() {
+        return dart.as(new LinkedHashSetIterator(this, this[_modifications]), core.Iterator$(E));
       }
-      lastKey() {
-        if (this[_root] === null)
-          return null;
-        return dart.as(this[_last].key, K);
+      get length() {
+        return this[_length];
       }
-      lastKeyBefore(key) {
-        if (key === null)
-          throw new core.ArgumentError(key);
-        if (this[_root] === null)
-          return null;
-        let comp = this[_splay](key);
-        if (dart.notNull(comp) < 0)
-          return this[_root].key;
-        let node = this[_root].left;
-        if (node === null)
-          return null;
-        while (node.right !== null) {
-          node = node.right;
-        }
-        return node.key;
+      get isEmpty() {
+        return this[_length] === 0;
       }
-      firstKeyAfter(key) {
-        if (key === null)
-          throw new core.ArgumentError(key);
-        if (this[_root] === null)
-          return null;
-        let comp = this[_splay](key);
-        if (dart.notNull(comp) > 0)
-          return this[_root].key;
-        let node = this[_root].right;
-        if (node === null)
-          return null;
-        while (node.left !== null) {
-          node = node.left;
+      get isNotEmpty() {
+        return !dart.notNull(this.isEmpty);
+      }
+      contains(object) {
+        if (_isStringElement(object)) {
+          let strings = this[_strings];
+          if (strings === null)
+            return false;
+          let cell = dart.as(_getTableEntry(strings, object), LinkedHashSetCell);
+          return cell !== null;
+        } else if (_isNumericElement(object)) {
+          let nums = this[_nums];
+          if (nums === null)
+            return false;
+          let cell = dart.as(_getTableEntry(nums, object), LinkedHashSetCell);
+          return cell !== null;
+        } else {
+          return this[_contains](object);
         }
-        return node.key;
       }
-    }
-    dart.defineNamedConstructor(SplayTreeMap, 'from');
-    dart.defineNamedConstructor(SplayTreeMap, 'fromIterable');
-    dart.defineNamedConstructor(SplayTreeMap, 'fromIterables');
-    dart.defineNamedConstructor(SplayTreeMap, '_internal');
-    return SplayTreeMap;
-  });
-  let SplayTreeMap = SplayTreeMap$(dynamic, dynamic);
-  let _workList = Symbol('_workList');
-  let _tree = Symbol('_tree');
-  let _currentNode = Symbol('_currentNode');
-  let _findLeftMostDescendent = Symbol('_findLeftMostDescendent');
-  let _getValue = Symbol('_getValue');
-  let _rebuildWorkList = Symbol('_rebuildWorkList');
-  let _SplayTreeIterator$ = dart.generic(function(T) {
-    class _SplayTreeIterator extends dart.Object {
-      _SplayTreeIterator(tree) {
-        this[_workList] = new List.from([]);
-        this[_tree] = tree;
-        this[_modificationCount] = tree[_modificationCount];
-        this[_splayCount] = tree[_splayCount];
-        this[_currentNode] = null;
-        this[_findLeftMostDescendent](tree[_root]);
+      [_contains](object) {
+        let rest = this[_rest];
+        if (rest === null)
+          return false;
+        let bucket = this[_getBucket](rest, object);
+        return dart.notNull(this[_findBucketIndex](bucket, object)) >= 0;
       }
-      _SplayTreeIterator$startAt(tree, startKey) {
-        this[_workList] = new List.from([]);
-        this[_tree] = tree;
-        this[_modificationCount] = tree[_modificationCount];
-        this[_splayCount] = null;
-        this[_currentNode] = null;
-        if (tree[_root] === null)
-          return;
-        let compare = tree._splay(startKey);
-        this[_splayCount] = tree[_splayCount];
-        if (dart.notNull(compare) < 0) {
-          this[_findLeftMostDescendent](tree[_root].right);
+      lookup(object) {
+        if (dart.notNull(_isStringElement(object)) || dart.notNull(_isNumericElement(object))) {
+          return dart.as(this.contains(object) ? object : null, E);
         } else {
-          this[_workList].add(tree[_root]);
+          return this[_lookup](object);
         }
       }
-      get current() {
-        if (this[_currentNode] === null)
+      [_lookup](object) {
+        let rest = this[_rest];
+        if (rest === null)
           return null;
-        return this[_getValue](this[_currentNode]);
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
+        if (dart.notNull(index) < 0)
+          return null;
+        return dart.as(dart.dload(bucket.get(index), '_element'), E);
       }
-      [_findLeftMostDescendent](node) {
-        while (node !== null) {
-          this[_workList].add(node);
-          node = node.left;
+      forEach(action) {
+        let cell = this[_first];
+        let modifications = this[_modifications];
+        while (cell !== null) {
+          action(dart.as(cell[_element], E));
+          if (modifications !== this[_modifications]) {
+            throw new core.ConcurrentModificationError(this);
+          }
+          cell = cell[_next];
         }
       }
-      [_rebuildWorkList](currentNode) {
-        dart.assert(!dart.notNull(this[_workList].isEmpty));
-        this[_workList].clear();
-        if (currentNode === null) {
-          this[_findLeftMostDescendent](this[_tree][_root]);
+      get first() {
+        if (this[_first] === null)
+          throw new core.StateError("No elements");
+        return dart.as(this[_first][_element], E);
+      }
+      get last() {
+        if (this[_last] === null)
+          throw new core.StateError("No elements");
+        return dart.as(this[_last][_element], E);
+      }
+      add(element) {
+        if (_isStringElement(element)) {
+          let strings = this[_strings];
+          if (strings === null)
+            this[_strings] = strings = _newHashTable();
+          return this[_addHashTableEntry](strings, element);
+        } else if (_isNumericElement(element)) {
+          let nums = this[_nums];
+          if (nums === null)
+            this[_nums] = nums = _newHashTable();
+          return this[_addHashTableEntry](nums, element);
         } else {
-          this[_tree]._splay(currentNode.key);
-          this[_findLeftMostDescendent](this[_tree][_root].right);
-          dart.assert(!dart.notNull(this[_workList].isEmpty));
+          return this[_add](element);
         }
       }
-      moveNext() {
-        if (this[_modificationCount] !== this[_tree][_modificationCount]) {
-          throw new core.ConcurrentModificationError(this[_tree]);
+      [_add](element) {
+        let rest = this[_rest];
+        if (rest === null)
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](element);
+        let bucket = rest[hash];
+        if (bucket === null) {
+          let cell = this[_newLinkedCell](element);
+          _setTableEntry(rest, hash, [cell]);
+        } else {
+          let index = this[_findBucketIndex](bucket, element);
+          if (dart.notNull(index) >= 0)
+            return false;
+          let cell = this[_newLinkedCell](element);
+          bucket.push(cell);
         }
-        if (this[_workList].isEmpty) {
-          this[_currentNode] = null;
+        return true;
+      }
+      remove(object) {
+        if (_isStringElement(object)) {
+          return this[_removeHashTableEntry](this[_strings], object);
+        } else if (_isNumericElement(object)) {
+          return this[_removeHashTableEntry](this[_nums], object);
+        } else {
+          return this[_remove](object);
+        }
+      }
+      [_remove](object) {
+        let rest = this[_rest];
+        if (rest === null)
           return false;
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
+        if (dart.notNull(index) < 0)
+          return false;
+        let cell = dart.as(bucket.splice(index, 1)[0], LinkedHashSetCell);
+        this[_unlinkCell](cell);
+        return true;
+      }
+      removeWhere(test) {
+        this[_filterWhere](test, true);
+      }
+      retainWhere(test) {
+        this[_filterWhere](test, false);
+      }
+      [_filterWhere](test, removeMatching) {
+        let cell = this[_first];
+        while (cell !== null) {
+          let element = dart.as(cell[_element], E);
+          let next = cell[_next];
+          let modifications = this[_modifications];
+          let shouldRemove = removeMatching === test(element);
+          if (modifications !== this[_modifications]) {
+            throw new core.ConcurrentModificationError(this);
+          }
+          if (shouldRemove)
+            this.remove(element);
+          cell = next;
         }
-        if (this[_tree][_splayCount] !== this[_splayCount] && dart.notNull(this[_currentNode] !== null)) {
-          this[_rebuildWorkList](this[_currentNode]);
+      }
+      clear() {
+        if (dart.notNull(this[_length]) > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_first] = this[_last] = null;
+          this[_length] = 0;
+          this[_modified]();
         }
-        this[_currentNode] = this[_workList].removeLast();
-        this[_findLeftMostDescendent](this[_currentNode].right);
+      }
+      [_addHashTableEntry](table, element) {
+        let cell = dart.as(_getTableEntry(table, element), LinkedHashSetCell);
+        if (cell !== null)
+          return false;
+        _setTableEntry(table, element, this[_newLinkedCell](element));
         return true;
       }
-    }
-    dart.defineNamedConstructor(_SplayTreeIterator, 'startAt');
-    return _SplayTreeIterator;
-  });
-  let _SplayTreeIterator = _SplayTreeIterator$(dynamic);
-  let _SplayTreeKeyIterable$ = dart.generic(function(K) {
-    class _SplayTreeKeyIterable extends IterableBase$(K) {
-      _SplayTreeKeyIterable($_tree) {
-        this[_tree] = $_tree;
-        super.IterableBase();
+      [_removeHashTableEntry](table, element) {
+        if (table === null)
+          return false;
+        let cell = dart.as(_getTableEntry(table, element), LinkedHashSetCell);
+        if (cell === null)
+          return false;
+        this[_unlinkCell](cell);
+        _deleteTableEntry(table, element);
+        return true;
       }
-      get length() {
-        return this[_tree][_count];
+      [_modified]() {
+        this[_modifications] = dart.notNull(this[_modifications]) + 1 & 67108863;
       }
-      get isEmpty() {
-        return this[_tree][_count] === 0;
+      [_newLinkedCell](element) {
+        let cell = new LinkedHashSetCell(element);
+        if (this[_first] === null) {
+          this[_first] = this[_last] = cell;
+        } else {
+          let last = this[_last];
+          cell[_previous] = last;
+          this[_last] = last[_next] = cell;
+        }
+        this[_length] = dart.notNull(this[_length]) + 1;
+        this[_modified]();
+        return cell;
       }
-      get iterator() {
-        return new _SplayTreeKeyIterator(this[_tree]);
+      [_unlinkCell](cell) {
+        let previous = cell[_previous];
+        let next = cell[_next];
+        if (previous === null) {
+          dart.assert(dart.equals(cell, this[_first]));
+          this[_first] = next;
+        } else {
+          previous[_next] = next;
+        }
+        if (next === null) {
+          dart.assert(dart.equals(cell, this[_last]));
+          this[_last] = previous;
+        } else {
+          next[_previous] = previous;
+        }
+        this[_length] = dart.notNull(this[_length]) - 1;
+        this[_modified]();
       }
-      toSet() {
-        let setOrMap = this[_tree];
-        let set = new SplayTreeSet(dart.as(setOrMap[_comparator], dart.throw_("Unimplemented type (K, K) → int")), dart.as(setOrMap[_validKey], dart.throw_("Unimplemented type (dynamic) → bool")));
-        set[_count] = this[_tree][_count];
-        set[_root] = set._copyNode(this[_tree][_root]);
-        return set;
+      static [_isStringElement](element) {
+        return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
       }
-    }
-    return _SplayTreeKeyIterable;
-  });
-  let _SplayTreeKeyIterable = _SplayTreeKeyIterable$(dynamic);
-  let _SplayTreeValueIterable$ = dart.generic(function(K, V) {
-    class _SplayTreeValueIterable extends IterableBase$(V) {
-      _SplayTreeValueIterable($_map) {
-        this[_map] = $_map;
-        super.IterableBase();
+      static [_isNumericElement](element) {
+        return dart.notNull(dart.is(element, core.num)) && (element & 0x3ffffff) === element;
       }
-      get length() {
-        return this[_map][_count];
+      [_computeHashCode](element) {
+        return dart.dload(element, 'hashCode') & 0x3ffffff;
       }
-      get isEmpty() {
-        return this[_map][_count] === 0;
+      static [_getTableEntry](table, key) {
+        return table[key];
       }
-      get iterator() {
-        return new _SplayTreeValueIterator(this[_map]);
+      static [_setTableEntry](table, key, value) {
+        dart.assert(value !== null);
+        table[key] = value;
       }
-    }
-    return _SplayTreeValueIterable;
-  });
-  let _SplayTreeValueIterable = _SplayTreeValueIterable$(dynamic, dynamic);
-  let _SplayTreeKeyIterator$ = dart.generic(function(K) {
-    class _SplayTreeKeyIterator extends _SplayTreeIterator$(K) {
-      _SplayTreeKeyIterator(map) {
-        super._SplayTreeIterator(map);
+      static [_deleteTableEntry](table, key) {
+        delete table[key];
       }
-      [_getValue](node) {
-        return dart.as(node.key, K);
+      [_getBucket](table, element) {
+        let hash = this[_computeHashCode](element);
+        return dart.as(table[hash], core.List);
       }
-    }
-    return _SplayTreeKeyIterator;
-  });
-  let _SplayTreeKeyIterator = _SplayTreeKeyIterator$(dynamic);
-  let _SplayTreeValueIterator$ = dart.generic(function(K, V) {
-    class _SplayTreeValueIterator extends _SplayTreeIterator$(V) {
-      _SplayTreeValueIterator(map) {
-        super._SplayTreeIterator(map);
+      [_findBucketIndex](bucket, element) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let cell = dart.as(bucket[i], LinkedHashSetCell);
+          if (dart.equals(cell[_element], element))
+            return i;
+        }
+        return -1;
       }
-      [_getValue](node) {
-        return dart.as(node.value, V);
+      static [_newHashTable]() {
+        let table = Object.create(null);
+        let temporaryKey = '<non-identifier-key>';
+        _setTableEntry(table, temporaryKey, table);
+        _deleteTableEntry(table, temporaryKey);
+        return table;
       }
     }
-    return _SplayTreeValueIterator;
+    return _LinkedHashSet;
   });
-  let _SplayTreeValueIterator = _SplayTreeValueIterator$(dynamic, dynamic);
-  let _SplayTreeNodeIterator$ = dart.generic(function(K) {
-    class _SplayTreeNodeIterator extends _SplayTreeIterator$(_SplayTreeNode$(K)) {
-      _SplayTreeNodeIterator(tree) {
-        super._SplayTreeIterator(tree);
+  let _LinkedHashSet = _LinkedHashSet$(dart.dynamic);
+  let _LinkedIdentityHashSet$ = dart.generic(function(E) {
+    class _LinkedIdentityHashSet extends _LinkedHashSet$(E) {
+      [_newSet]() {
+        return new _LinkedIdentityHashSet();
       }
-      _SplayTreeNodeIterator$startAt(tree, startKey) {
-        super._SplayTreeIterator$startAt(tree, startKey);
+      [_computeHashCode](key) {
+        return core.identityHashCode(key) & 0x3ffffff;
       }
-      [_getValue](node) {
-        return dart.as(node, _SplayTreeNode$(K));
+      [_findBucketIndex](bucket, element) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let cell = dart.as(bucket[i], LinkedHashSetCell);
+          if (core.identical(cell[_element], element))
+            return i;
+        }
+        return -1;
       }
     }
-    dart.defineNamedConstructor(_SplayTreeNodeIterator, 'startAt');
-    return _SplayTreeNodeIterator;
+    return _LinkedIdentityHashSet;
   });
-  let _SplayTreeNodeIterator = _SplayTreeNodeIterator$(dynamic);
-  let _clone = Symbol('_clone');
-  let _copyNode = Symbol('_copyNode');
-  let SplayTreeSet$ = dart.generic(function(E) {
-    class SplayTreeSet extends dart.mixin(_SplayTree$(E), IterableMixin$(E), SetMixin$(E)) {
-      SplayTreeSet(compare, isValidKey) {
-        if (compare === void 0)
-          compare = null;
-        if (isValidKey === void 0)
-          isValidKey = null;
-        this[_comparator] = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
-        this[_validKey] = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, E), _Predicate);
-        super._SplayTree();
-      }
-      SplayTreeSet$from(elements, compare, isValidKey) {
-        if (compare === void 0)
-          compare = null;
-        if (isValidKey === void 0)
-          isValidKey = null;
-        let result = new SplayTreeSet(compare, isValidKey);
-        for (let element of elements) {
-          result.add(element);
-        }
-        return result;
-      }
-      [_compare](e1, e2) {
-        return this[_comparator](e1, e2);
-      }
-      get iterator() {
-        return new _SplayTreeKeyIterator(this);
-      }
-      get length() {
-        return this[_count];
-      }
-      get isEmpty() {
-        return this[_root] === null;
+  let _LinkedIdentityHashSet = _LinkedIdentityHashSet$(dart.dynamic);
+  let _LinkedCustomHashSet$ = dart.generic(function(E) {
+    class _LinkedCustomHashSet extends _LinkedHashSet$(E) {
+      _LinkedCustomHashSet($_equality, $_hasher, validKey) {
+        this[_equality] = $_equality;
+        this[_hasher] = $_hasher;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
+        super._LinkedHashSet();
       }
-      get isNotEmpty() {
-        return this[_root] !== null;
+      [_newSet]() {
+        return new _LinkedCustomHashSet(this[_equality], this[_hasher], this[_validKey]);
       }
-      get first() {
-        if (this[_count] === 0)
-          throw _internal.IterableElementError.noElement();
-        return dart.as(this[_first].key, E);
+      [_findBucketIndex](bucket, element) {
+        if (bucket === null)
+          return -1;
+        let length = bucket.length;
+        for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
+          let cell = dart.as(bucket[i], LinkedHashSetCell);
+          if (this[_equality](dart.as(cell[_element], E), dart.as(element, E)))
+            return i;
+        }
+        return -1;
       }
-      get last() {
-        if (this[_count] === 0)
-          throw _internal.IterableElementError.noElement();
-        return dart.as(this[_last].key, E);
+      [_computeHashCode](element) {
+        return this[_hasher](dart.as(element, E)) & 0x3ffffff;
       }
-      get single() {
-        if (this[_count] === 0)
-          throw _internal.IterableElementError.noElement();
-        if (dart.notNull(this[_count]) > 1)
-          throw _internal.IterableElementError.tooMany();
-        return this[_root].key;
+      add(element) {
+        return super._add(element);
       }
       contains(object) {
-        return dart.notNull(this[_validKey](object)) && this[_splay](dart.as(object, E)) === 0;
-      }
-      add(element) {
-        let compare = this[_splay](element);
-        if (compare === 0)
+        if (!dart.notNull(this[_validKey](object)))
           return false;
-        this[_addNewRoot](dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
-        return true;
+        return super._contains(object);
+      }
+      lookup(object) {
+        if (!dart.notNull(this[_validKey](object)))
+          return null;
+        return super._lookup(object);
       }
       remove(object) {
         if (!dart.notNull(this[_validKey](object)))
           return false;
-        return this[_remove](dart.as(object, E)) !== null;
+        return super._remove(object);
       }
-      addAll(elements) {
+      containsAll(elements) {
         for (let element of elements) {
-          let compare = this[_splay](element);
-          if (compare !== 0) {
-            this[_addNewRoot](dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
-          }
+          if (!dart.notNull(this[_validKey](element)) || !dart.notNull(this.contains(element)))
+            return false;
         }
+        return true;
       }
       removeAll(elements) {
         for (let element of elements) {
-          if (this[_validKey](element))
-            this[_remove](dart.as(element, E));
-        }
-      }
-      retainAll(elements) {
-        let retainSet = new SplayTreeSet(this[_comparator], this[_validKey]);
-        let modificationCount = this[_modificationCount];
-        for (let object of elements) {
-          if (modificationCount !== this[_modificationCount]) {
-            throw new core.ConcurrentModificationError(this);
+          if (this[_validKey](element)) {
+            super._remove(element);
           }
-          if (dart.notNull(this[_validKey](object)) && this[_splay](dart.as(object, E)) === 0)
-            retainSet.add(this[_root].key);
-        }
-        if (retainSet[_count] !== this[_count]) {
-          this[_root] = retainSet[_root];
-          this[_count] = retainSet[_count];
-          this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
         }
       }
-      lookup(object) {
-        if (!dart.notNull(this[_validKey](object)))
-          return null;
-        let comp = this[_splay](dart.as(object, E));
-        if (comp !== 0)
-          return null;
-        return this[_root].key;
+    }
+    return _LinkedCustomHashSet;
+  });
+  let _LinkedCustomHashSet = _LinkedCustomHashSet$(dart.dynamic);
+  class LinkedHashSetCell extends core.Object {
+    LinkedHashSetCell($_element) {
+      this[_element] = $_element;
+      this[_next] = null;
+      this[_previous] = null;
+    }
+  }
+  let LinkedHashSetIterator$ = dart.generic(function(E) {
+    class LinkedHashSetIterator extends core.Object {
+      LinkedHashSetIterator($_set, $_modifications) {
+        this[_set] = $_set;
+        this[_modifications] = $_modifications;
+        this[_cell] = null;
+        this[_current] = null;
+        this[_cell] = dart.as(dart.dload(this[_set], '_first'), LinkedHashSetCell);
       }
-      intersection(other) {
-        let result = new SplayTreeSet(this[_comparator], this[_validKey]);
-        for (let element of this) {
-          if (other.contains(element))
-            result.add(element);
-        }
-        return result;
+      get current() {
+        return this[_current];
       }
-      difference(other) {
-        let result = new SplayTreeSet(this[_comparator], this[_validKey]);
-        for (let element of this) {
-          if (!dart.notNull(other.contains(element)))
-            result.add(element);
+      moveNext() {
+        if (this[_modifications] !== dart.dload(this[_set], '_modifications')) {
+          throw new core.ConcurrentModificationError(this[_set]);
+        } else if (this[_cell] === null) {
+          this[_current] = null;
+          return false;
+        } else {
+          this[_current] = dart.as(this[_cell][_element], E);
+          this[_cell] = this[_cell][_next];
+          return true;
         }
-        return result;
-      }
-      union(other) {
-        return ((_) => {
-          _.addAll(other);
-          return _;
-        }).bind(this)(this[_clone]());
-      }
-      [_clone]() {
-        let set = new SplayTreeSet(this[_comparator], this[_validKey]);
-        set[_count] = this[_count];
-        set[_root] = this[_copyNode](this[_root]);
-        return set;
-      }
-      [_copyNode](node) {
-        if (node === null)
-          return null;
-        return ((_) => {
-          _.left = this[_copyNode](node.left);
-          _.right = this[_copyNode](node.right);
-          return _;
-        }).bind(this)(new _SplayTreeNode(node.key));
-      }
-      clear() {
-        this[_clear]();
-      }
-      toSet() {
-        return this[_clone]();
-      }
-      toString() {
-        return IterableBase.iterableToFullString(this, '{', '}');
       }
     }
-    dart.defineNamedConstructor(SplayTreeSet, 'from');
-    return SplayTreeSet;
+    return LinkedHashSetIterator;
   });
-  let SplayTreeSet = SplayTreeSet$(dynamic);
+  let LinkedHashSetIterator = LinkedHashSetIterator$(dart.dynamic);
   // Exports:
-  exports.HashMapKeyIterable = HashMapKeyIterable;
-  exports.HashMapKeyIterable$ = HashMapKeyIterable$;
-  exports.HashMapKeyIterator = HashMapKeyIterator;
-  exports.HashMapKeyIterator$ = HashMapKeyIterator$;
-  exports.LinkedHashMapCell = LinkedHashMapCell;
-  exports.LinkedHashMapKeyIterable = LinkedHashMapKeyIterable;
-  exports.LinkedHashMapKeyIterable$ = LinkedHashMapKeyIterable$;
-  exports.LinkedHashMapKeyIterator = LinkedHashMapKeyIterator;
-  exports.LinkedHashMapKeyIterator$ = LinkedHashMapKeyIterator$;
-  exports.HashSetIterator = HashSetIterator;
-  exports.HashSetIterator$ = HashSetIterator$;
-  exports.LinkedHashSetCell = LinkedHashSetCell;
-  exports.LinkedHashSetIterator = LinkedHashSetIterator;
-  exports.LinkedHashSetIterator$ = LinkedHashSetIterator$;
   exports.UnmodifiableListView = UnmodifiableListView;
   exports.UnmodifiableListView$ = UnmodifiableListView$;
   exports.HashMap = HashMap;
@@ -4896,4 +4882,18 @@ var collection;
   exports.SplayTreeMap$ = SplayTreeMap$;
   exports.SplayTreeSet = SplayTreeSet;
   exports.SplayTreeSet$ = SplayTreeSet$;
+  exports.HashMapKeyIterable = HashMapKeyIterable;
+  exports.HashMapKeyIterable$ = HashMapKeyIterable$;
+  exports.HashMapKeyIterator = HashMapKeyIterator;
+  exports.HashMapKeyIterator$ = HashMapKeyIterator$;
+  exports.LinkedHashMapCell = LinkedHashMapCell;
+  exports.LinkedHashMapKeyIterable = LinkedHashMapKeyIterable;
+  exports.LinkedHashMapKeyIterable$ = LinkedHashMapKeyIterable$;
+  exports.LinkedHashMapKeyIterator = LinkedHashMapKeyIterator;
+  exports.LinkedHashMapKeyIterator$ = LinkedHashMapKeyIterator$;
+  exports.HashSetIterator = HashSetIterator;
+  exports.HashSetIterator$ = HashSetIterator$;
+  exports.LinkedHashSetCell = LinkedHashSetCell;
+  exports.LinkedHashSetIterator = LinkedHashSetIterator;
+  exports.LinkedHashSetIterator$ = LinkedHashSetIterator$;
 })(collection || (collection = {}));